diff --git a/docs/reference-guides/theme-json-reference/theme-json-living.md b/docs/reference-guides/theme-json-reference/theme-json-living.md
index 6d0c02e8d27ed3..bb2ce78584b2bc 100644
--- a/docs/reference-guides/theme-json-reference/theme-json-living.md
+++ b/docs/reference-guides/theme-json-reference/theme-json-living.md
@@ -83,6 +83,9 @@ Settings related to spacing.
 | margin | boolean | false |  |
 | padding | boolean | false |  |
 | units | array | px,em,rem,vh,vw,% |  |
+| customSpacingSize | boolean | true |  |
+| spacingSizes | array |  | name, size, slug |
+| spacingScale | object |  |  |
 
 ---
 
diff --git a/lib/compat/wordpress-6.0/block-editor-settings.php b/lib/compat/wordpress-6.0/block-editor-settings.php
index 9030998aed250f..21f1f05bb45f1f 100644
--- a/lib/compat/wordpress-6.0/block-editor-settings.php
+++ b/lib/compat/wordpress-6.0/block-editor-settings.php
@@ -47,149 +47,3 @@ function gutenberg_is_global_styles_in_5_9( $style ) {
 
 	return false;
 }
-
-/**
- * Adds styles and __experimentalFeatures to the block editor settings.
- *
- * @param array $settings Existing block editor settings.
- *
- * @return array New block editor settings.
- */
-function gutenberg_get_block_editor_settings( $settings ) {
-	// Set what is the context for this data request.
-	$context = 'other';
-	if (
-		defined( 'REST_REQUEST' ) &&
-		REST_REQUEST &&
-		isset( $_GET['context'] ) &&
-		'mobile' === $_GET['context']
-	) {
-		$context = 'mobile';
-	}
-
-	if ( 'other' === $context ) {
-		global $wp_version;
-		$is_wp_5_8 = version_compare( $wp_version, '5.8', '>=' ) && version_compare( $wp_version, '5.9', '<' );
-		$is_wp_5_9 = version_compare( $wp_version, '5.9', '>=' ) && version_compare( $wp_version, '6.0-beta1', '<' );
-		$is_wp_6_0 = version_compare( $wp_version, '6.0-beta1', '>=' );
-
-		// Make sure the styles array exists.
-		// In some contexts, like the navigation editor, it doesn't.
-		if ( ! isset( $settings['styles'] ) ) {
-			$settings['styles'] = array();
-		}
-
-		// Remove existing global styles provided by core.
-		$styles_without_existing_global_styles = array();
-		foreach ( $settings['styles'] as $style ) {
-			if (
-				( $is_wp_5_8 && ! gutenberg_is_global_styles_in_5_8( $style ) ) || // Can be removed when plugin minimum version is 5.9.
-				( $is_wp_5_9 && ! gutenberg_is_global_styles_in_5_9( $style ) ) || // Can be removed when plugin minimum version is 6.0.
-				( $is_wp_6_0 && ( ! isset( $style['isGlobalStyles'] ) || ! $style['isGlobalStyles'] ) )
-			) {
-				$styles_without_existing_global_styles[] = $style;
-			}
-		}
-
-		// Recreate global styles.
-		$new_global_styles = array();
-		$presets           = array(
-			array(
-				'css'            => 'variables',
-				'__unstableType' => 'presets',
-				'isGlobalStyles' => true,
-			),
-			array(
-				'css'            => 'presets',
-				'__unstableType' => 'presets',
-				'isGlobalStyles' => true,
-			),
-		);
-		foreach ( $presets as $preset_style ) {
-			$actual_css = gutenberg_get_global_stylesheet( array( $preset_style['css'] ) );
-			if ( '' !== $actual_css ) {
-				$preset_style['css'] = $actual_css;
-				$new_global_styles[] = $preset_style;
-			}
-		}
-
-		if ( WP_Theme_JSON_Resolver::theme_has_support() ) {
-			$block_classes = array(
-				'css'            => 'styles',
-				'__unstableType' => 'theme',
-				'isGlobalStyles' => true,
-			);
-			$actual_css    = gutenberg_get_global_stylesheet( array( $block_classes['css'] ) );
-			if ( '' !== $actual_css ) {
-				$block_classes['css'] = $actual_css;
-				$new_global_styles[]  = $block_classes;
-			}
-		}
-
-		$settings['styles'] = array_merge( $new_global_styles, $styles_without_existing_global_styles );
-	}
-
-	// Copied from get_block_editor_settings() at wordpress-develop/block-editor.php.
-	$settings['__experimentalFeatures'] = gutenberg_get_global_settings();
-
-	if ( isset( $settings['__experimentalFeatures']['color']['palette'] ) ) {
-		$colors_by_origin   = $settings['__experimentalFeatures']['color']['palette'];
-		$settings['colors'] = isset( $colors_by_origin['custom'] ) ?
-			$colors_by_origin['custom'] : (
-				isset( $colors_by_origin['theme'] ) ?
-					$colors_by_origin['theme'] :
-					$colors_by_origin['default']
-			);
-	}
-
-	if ( isset( $settings['__experimentalFeatures']['color']['gradients'] ) ) {
-		$gradients_by_origin   = $settings['__experimentalFeatures']['color']['gradients'];
-		$settings['gradients'] = isset( $gradients_by_origin['custom'] ) ?
-			$gradients_by_origin['custom'] : (
-				isset( $gradients_by_origin['theme'] ) ?
-					$gradients_by_origin['theme'] :
-					$gradients_by_origin['default']
-			);
-	}
-
-	if ( isset( $settings['__experimentalFeatures']['typography']['fontSizes'] ) ) {
-		$font_sizes_by_origin  = $settings['__experimentalFeatures']['typography']['fontSizes'];
-		$settings['fontSizes'] = isset( $font_sizes_by_origin['custom'] ) ?
-			$font_sizes_by_origin['custom'] : (
-				isset( $font_sizes_by_origin['theme'] ) ?
-					$font_sizes_by_origin['theme'] :
-					$font_sizes_by_origin['default']
-			);
-	}
-
-	if ( isset( $settings['__experimentalFeatures']['color']['custom'] ) ) {
-		$settings['disableCustomColors'] = ! $settings['__experimentalFeatures']['color']['custom'];
-		unset( $settings['__experimentalFeatures']['color']['custom'] );
-	}
-	if ( isset( $settings['__experimentalFeatures']['color']['customGradient'] ) ) {
-		$settings['disableCustomGradients'] = ! $settings['__experimentalFeatures']['color']['customGradient'];
-		unset( $settings['__experimentalFeatures']['color']['customGradient'] );
-	}
-	if ( isset( $settings['__experimentalFeatures']['typography']['customFontSize'] ) ) {
-		$settings['disableCustomFontSizes'] = ! $settings['__experimentalFeatures']['typography']['customFontSize'];
-		unset( $settings['__experimentalFeatures']['typography']['customFontSize'] );
-	}
-	if ( isset( $settings['__experimentalFeatures']['typography']['lineHeight'] ) ) {
-		$settings['enableCustomLineHeight'] = $settings['__experimentalFeatures']['typography']['lineHeight'];
-		unset( $settings['__experimentalFeatures']['typography']['lineHeight'] );
-	}
-	if ( isset( $settings['__experimentalFeatures']['spacing']['units'] ) ) {
-		$settings['enableCustomUnits'] = $settings['__experimentalFeatures']['spacing']['units'];
-		unset( $settings['__experimentalFeatures']['spacing']['units'] );
-	}
-	if ( isset( $settings['__experimentalFeatures']['spacing']['padding'] ) ) {
-		$settings['enableCustomSpacing'] = $settings['__experimentalFeatures']['spacing']['padding'];
-		unset( $settings['__experimentalFeatures']['spacing']['padding'] );
-	}
-
-	$settings['localAutosaveInterval'] = 15;
-
-	return $settings;
-}
-
-add_filter( 'block_editor_settings_all', 'gutenberg_get_block_editor_settings', PHP_INT_MAX );
diff --git a/lib/compat/wordpress-6.1/block-editor-settings.php b/lib/compat/wordpress-6.1/block-editor-settings.php
new file mode 100644
index 00000000000000..ed591cf60196ae
--- /dev/null
+++ b/lib/compat/wordpress-6.1/block-editor-settings.php
@@ -0,0 +1,166 @@
+<?php
+/**
+ * Adds settings to the block editor.
+ *
+ * @package gutenberg
+ */
+
+/**
+ * Adds styles and __experimentalFeatures to the block editor settings.
+ *
+ * @param array $settings Existing block editor settings.
+ *
+ * @return array New block editor settings.
+ */
+function gutenberg_get_block_editor_settings( $settings ) {
+	// Set what is the context for this data request.
+	$context = 'other';
+	if (
+		defined( 'REST_REQUEST' ) &&
+		REST_REQUEST &&
+		isset( $_GET['context'] ) &&
+		'mobile' === $_GET['context']
+	) {
+		$context = 'mobile';
+	}
+
+	if ( 'other' === $context ) {
+		global $wp_version;
+		$is_wp_5_8 = version_compare( $wp_version, '5.8', '>=' ) && version_compare( $wp_version, '5.9', '<' );
+		$is_wp_5_9 = version_compare( $wp_version, '5.9', '>=' ) && version_compare( $wp_version, '6.0-beta1', '<' );
+		$is_wp_6_0 = version_compare( $wp_version, '6.0-beta1', '>=' );
+
+		// Make sure the styles array exists.
+		// In some contexts, like the navigation editor, it doesn't.
+		if ( ! isset( $settings['styles'] ) ) {
+			$settings['styles'] = array();
+		}
+
+		// Remove existing global styles provided by core.
+		$styles_without_existing_global_styles = array();
+		foreach ( $settings['styles'] as $style ) {
+			if (
+				( $is_wp_5_8 && ! gutenberg_is_global_styles_in_5_8( $style ) ) || // Can be removed when plugin minimum version is 5.9.
+				( $is_wp_5_9 && ! gutenberg_is_global_styles_in_5_9( $style ) ) || // Can be removed when plugin minimum version is 6.0.
+				( $is_wp_6_0 && ( ! isset( $style['isGlobalStyles'] ) || ! $style['isGlobalStyles'] ) )
+			) {
+				$styles_without_existing_global_styles[] = $style;
+			}
+		}
+
+		// Recreate global styles.
+		$new_global_styles = array();
+		$presets           = array(
+			array(
+				'css'            => 'variables',
+				'__unstableType' => 'presets',
+				'isGlobalStyles' => true,
+			),
+			array(
+				'css'            => 'presets',
+				'__unstableType' => 'presets',
+				'isGlobalStyles' => true,
+			),
+		);
+		foreach ( $presets as $preset_style ) {
+			$actual_css = gutenberg_get_global_stylesheet( array( $preset_style['css'] ) );
+			if ( '' !== $actual_css ) {
+				$preset_style['css'] = $actual_css;
+				$new_global_styles[] = $preset_style;
+			}
+		}
+
+		if ( WP_Theme_JSON_Resolver::theme_has_support() ) {
+			$block_classes = array(
+				'css'            => 'styles',
+				'__unstableType' => 'theme',
+				'isGlobalStyles' => true,
+			);
+			$actual_css    = gutenberg_get_global_stylesheet( array( $block_classes['css'] ) );
+			if ( '' !== $actual_css ) {
+				$block_classes['css'] = $actual_css;
+				$new_global_styles[]  = $block_classes;
+			}
+		}
+
+		$settings['styles'] = array_merge( $new_global_styles, $styles_without_existing_global_styles );
+	}
+
+	// Copied from get_block_editor_settings() at wordpress-develop/block-editor.php.
+	$settings['__experimentalFeatures'] = gutenberg_get_global_settings();
+
+	if ( isset( $settings['__experimentalFeatures']['color']['palette'] ) ) {
+		$colors_by_origin   = $settings['__experimentalFeatures']['color']['palette'];
+		$settings['colors'] = isset( $colors_by_origin['custom'] ) ?
+			$colors_by_origin['custom'] : (
+				isset( $colors_by_origin['theme'] ) ?
+					$colors_by_origin['theme'] :
+					$colors_by_origin['default']
+			);
+	}
+
+	if ( isset( $settings['__experimentalFeatures']['color']['gradients'] ) ) {
+		$gradients_by_origin   = $settings['__experimentalFeatures']['color']['gradients'];
+		$settings['gradients'] = isset( $gradients_by_origin['custom'] ) ?
+			$gradients_by_origin['custom'] : (
+				isset( $gradients_by_origin['theme'] ) ?
+					$gradients_by_origin['theme'] :
+					$gradients_by_origin['default']
+			);
+	}
+
+	if ( isset( $settings['__experimentalFeatures']['typography']['fontSizes'] ) ) {
+		$font_sizes_by_origin  = $settings['__experimentalFeatures']['typography']['fontSizes'];
+		$settings['fontSizes'] = isset( $font_sizes_by_origin['custom'] ) ?
+			$font_sizes_by_origin['custom'] : (
+				isset( $font_sizes_by_origin['theme'] ) ?
+					$font_sizes_by_origin['theme'] :
+					$font_sizes_by_origin['default']
+			);
+	}
+
+	if ( isset( $settings['__experimentalFeatures']['color']['custom'] ) ) {
+		$settings['disableCustomColors'] = ! $settings['__experimentalFeatures']['color']['custom'];
+		unset( $settings['__experimentalFeatures']['color']['custom'] );
+	}
+	if ( isset( $settings['__experimentalFeatures']['color']['customGradient'] ) ) {
+		$settings['disableCustomGradients'] = ! $settings['__experimentalFeatures']['color']['customGradient'];
+		unset( $settings['__experimentalFeatures']['color']['customGradient'] );
+	}
+	if ( isset( $settings['__experimentalFeatures']['typography']['customFontSize'] ) ) {
+		$settings['disableCustomFontSizes'] = ! $settings['__experimentalFeatures']['typography']['customFontSize'];
+		unset( $settings['__experimentalFeatures']['typography']['customFontSize'] );
+	}
+	if ( isset( $settings['__experimentalFeatures']['typography']['lineHeight'] ) ) {
+		$settings['enableCustomLineHeight'] = $settings['__experimentalFeatures']['typography']['lineHeight'];
+		unset( $settings['__experimentalFeatures']['typography']['lineHeight'] );
+	}
+	if ( isset( $settings['__experimentalFeatures']['spacing']['units'] ) ) {
+		$settings['enableCustomUnits'] = $settings['__experimentalFeatures']['spacing']['units'];
+		unset( $settings['__experimentalFeatures']['spacing']['units'] );
+	}
+	if ( isset( $settings['__experimentalFeatures']['spacing']['padding'] ) ) {
+		$settings['enableCustomSpacing'] = $settings['__experimentalFeatures']['spacing']['padding'];
+		unset( $settings['__experimentalFeatures']['spacing']['padding'] );
+	}
+	if ( isset( $settings['__experimentalFeatures']['spacing']['customSpacingSize'] ) ) {
+		$settings['disableCustomSpacingSize'] = ! $settings['__experimentalFeatures']['spacing']['customSpacingSize'];
+		unset( $settings['__experimentalFeatures']['spacing']['customSpacingSize'] );
+	}
+
+	if ( isset( $settings['__experimentalFeatures']['spacing']['spacingSizes'] ) ) {
+		$spacing_sizes_by_origin  = $settings['__experimentalFeatures']['spacing']['spacingSizes'];
+		$settings['spacingSizes'] = isset( $spacing_sizes_by_origin['custom'] ) ?
+			$spacing_sizes_by_origin['custom'] : (
+				isset( $spacing_sizes_by_origin['theme'] ) ?
+					$spacing_sizes_by_origin['theme'] :
+					$spacing_sizes_by_origin['default']
+			);
+	}
+
+	$settings['localAutosaveInterval'] = 15;
+
+	return $settings;
+}
+
+add_filter( 'block_editor_settings_all', 'gutenberg_get_block_editor_settings', PHP_INT_MAX );
diff --git a/lib/compat/wordpress-6.1/class-wp-theme-json-6-1.php b/lib/compat/wordpress-6.1/class-wp-theme-json-6-1.php
index 946680fb44bdd7..f0b18bc2ab2d5f 100644
--- a/lib/compat/wordpress-6.1/class-wp-theme-json-6-1.php
+++ b/lib/compat/wordpress-6.1/class-wp-theme-json-6-1.php
@@ -322,4 +322,341 @@ protected function get_block_classes( $style_nodes ) {
 
 		return $block_rules;
 	}
+
+	/**
+	 * Presets are a set of values that serve
+	 * to bootstrap some styles: colors, font sizes, etc.
+	 *
+	 * They are a unkeyed array of values such as:
+	 *
+	 * ```php
+	 * array(
+	 *   array(
+	 *     'slug'      => 'unique-name-within-the-set',
+	 *     'name'      => 'Name for the UI',
+	 *     <value_key> => 'value'
+	 *   ),
+	 * )
+	 * ```
+	 *
+	 * This contains the necessary metadata to process them:
+	 *
+	 * - path             => Where to find the preset within the settings section.
+	 * - prevent_override => Disables override of default presets by theme presets.
+	 *                       The relationship between whether to override the defaults
+	 *                       and whether the defaults are enabled is inverse:
+	 *                         - If defaults are enabled  => theme presets should not be overriden
+	 *                         - If defaults are disabled => theme presets should be overriden
+	 *                       For example, a theme sets defaultPalette to false,
+	 *                       making the default palette hidden from the user.
+	 *                       In that case, we want all the theme presets to be present,
+	 *                       so they should override the defaults by setting this false.
+	 * - use_default_names => whether to use the default names
+	 * - value_key        => the key that represents the value
+	 * - value_func       => optionally, instead of value_key, a function to generate
+	 *                       the value that takes a preset as an argument
+	 *                       (either value_key or value_func should be present)
+	 * - css_vars         => template string to use in generating the CSS Custom Property.
+	 *                       Example output: "--wp--preset--duotone--blue: <value>" will generate as many CSS Custom Properties as presets defined
+	 *                       substituting the $slug for the slug's value for each preset value.
+	 * - classes          => array containing a structure with the classes to
+	 *                       generate for the presets, where for each array item
+	 *                       the key is the class name and the value the property name.
+	 *                       The "$slug" substring will be replaced by the slug of each preset.
+	 *                       For example:
+	 *                       'classes' => array(
+	 *                         '.has-$slug-color'            => 'color',
+	 *                         '.has-$slug-background-color' => 'background-color',
+	 *                         '.has-$slug-border-color'     => 'border-color',
+	 *                       )
+	 * - properties       => array of CSS properties to be used by kses to
+	 *                       validate the content of each preset
+	 *                       by means of the remove_insecure_properties method.
+	 */
+	const PRESETS_METADATA = array(
+		array(
+			'path'              => array( 'color', 'palette' ),
+			'prevent_override'  => array( 'color', 'defaultPalette' ),
+			'use_default_names' => false,
+			'value_key'         => 'color',
+			'css_vars'          => '--wp--preset--color--$slug',
+			'classes'           => array(
+				'.has-$slug-color'            => 'color',
+				'.has-$slug-background-color' => 'background-color',
+				'.has-$slug-border-color'     => 'border-color',
+			),
+			'properties'        => array( 'color', 'background-color', 'border-color' ),
+		),
+		array(
+			'path'              => array( 'color', 'gradients' ),
+			'prevent_override'  => array( 'color', 'defaultGradients' ),
+			'use_default_names' => false,
+			'value_key'         => 'gradient',
+			'css_vars'          => '--wp--preset--gradient--$slug',
+			'classes'           => array( '.has-$slug-gradient-background' => 'background' ),
+			'properties'        => array( 'background' ),
+		),
+		array(
+			'path'              => array( 'color', 'duotone' ),
+			'prevent_override'  => array( 'color', 'defaultDuotone' ),
+			'use_default_names' => false,
+			'value_func'        => 'gutenberg_get_duotone_filter_property',
+			'css_vars'          => '--wp--preset--duotone--$slug',
+			'classes'           => array(),
+			'properties'        => array( 'filter' ),
+		),
+		array(
+			'path'              => array( 'typography', 'fontSizes' ),
+			'prevent_override'  => false,
+			'use_default_names' => true,
+			'value_key'         => 'size',
+			'css_vars'          => '--wp--preset--font-size--$slug',
+			'classes'           => array( '.has-$slug-font-size' => 'font-size' ),
+			'properties'        => array( 'font-size' ),
+		),
+		array(
+			'path'              => array( 'typography', 'fontFamilies' ),
+			'prevent_override'  => false,
+			'use_default_names' => false,
+			'value_key'         => 'fontFamily',
+			'css_vars'          => '--wp--preset--font-family--$slug',
+			'classes'           => array( '.has-$slug-font-family' => 'font-family' ),
+			'properties'        => array( 'font-family' ),
+		),
+		array(
+			'path'              => array( 'spacing', 'spacingSizes' ),
+			'prevent_override'  => false,
+			'use_default_names' => true,
+			'value_key'         => 'size',
+			'css_vars'          => '--wp--preset--spacing--$slug',
+			'classes'           => array(),
+			'properties'        => array( 'padding', 'margin' ),
+		),
+		array(
+			'path'              => array( 'spacing', 'spacingScale' ),
+			'prevent_override'  => false,
+			'use_default_names' => true,
+			'value_key'         => 'size',
+			'css_vars'          => '--wp--preset--spacing--$slug',
+			'classes'           => array(),
+			'properties'        => array( 'padding', 'margin' ),
+		),
+	);
+
+	/**
+	 * The valid properties under the settings key.
+	 *
+	 * @var array
+	 */
+	const VALID_SETTINGS = array(
+		'appearanceTools' => null,
+		'border'          => array(
+			'color'  => null,
+			'radius' => null,
+			'style'  => null,
+			'width'  => null,
+		),
+		'color'           => array(
+			'background'       => null,
+			'custom'           => null,
+			'customDuotone'    => null,
+			'customGradient'   => null,
+			'defaultGradients' => null,
+			'defaultPalette'   => null,
+			'duotone'          => null,
+			'gradients'        => null,
+			'link'             => null,
+			'palette'          => null,
+			'text'             => null,
+		),
+		'custom'          => null,
+		'layout'          => array(
+			'contentSize' => null,
+			'wideSize'    => null,
+		),
+		'spacing'         => array(
+			'customSpacingSize' => null,
+			'spacingSizes'      => null,
+			'spacingScale'      => null,
+			'blockGap'          => null,
+			'margin'            => null,
+			'padding'           => null,
+			'units'             => null,
+		),
+		'typography'      => array(
+			'customFontSize' => null,
+			'dropCap'        => null,
+			'fontFamilies'   => null,
+			'fontSizes'      => null,
+			'fontStyle'      => null,
+			'fontWeight'     => null,
+			'letterSpacing'  => null,
+			'lineHeight'     => null,
+			'textDecoration' => null,
+			'textTransform'  => null,
+		),
+	);
+
+	/**
+	 * Transform the spacing scale values into an array of spacing scale presets.
+	 */
+	public function get_spacing_sizes() {
+		$spacing_scale = _wp_array_get( $this->theme_json, array( 'settings', 'spacing', 'spacingScale' ), array() );
+
+		if ( ! is_numeric( $spacing_scale['steps'] )
+			|| ! $spacing_scale['steps'] > 0
+			|| ! isset( $spacing_scale['mediumStep'] )
+			|| ! isset( $spacing_scale['units'] )
+			|| ! isset( $spacing_scale['operator'] )
+			|| ! isset( $spacing_scale['increment'] )
+			|| ! isset( $spacing_scale['steps'] )
+			|| ! is_numeric( $spacing_scale['increment'] )
+			|| ! is_numeric( $spacing_scale['mediumStep'] )
+			|| ( '+' !== $spacing_scale['operator'] && '*' !== $spacing_scale['operator'] ) ) {
+			if ( ! empty( $spacing_scale ) ) {
+				trigger_error( __( 'Some of the theme.json settings.spacing.spacingScale values are invalid', 'gutenberg' ), E_USER_NOTICE );
+			}
+			return null;
+		}
+
+		$current_step    = $spacing_scale['mediumStep'];
+		$steps_mid_point = round( ( ( $spacing_scale['steps'] ) / 2 ), 0 );
+
+		$x_count     = null;
+		$below_sizes = array();
+
+		for ( $x = $steps_mid_point - 1; $x > 0; $x-- ) {
+			$current_step = '+' === $spacing_scale['operator']
+				? $current_step - $spacing_scale['increment']
+				: $current_step / $spacing_scale['increment'];
+
+			$below_sizes[] = array(
+				/* translators: %s: Muliple of t-shirt sizing, eg. 2X-Small */
+				'name' => $x === $steps_mid_point - 1 ? __( 'Small', 'gutenberg' ) : sprintf( __( '%sX-Small', 'gutenberg' ), strval( $x_count ) ),
+				'slug' => $x * 10,
+				'size' => round( $current_step, 2 ) . $spacing_scale['units'],
+			);
+			if ( $x === $steps_mid_point - 2 ) {
+				$x_count = 2;
+			}
+			if ( $x < $steps_mid_point - 2 ) {
+				$x_count++;
+			}
+		}
+
+		$below_sizes = array_reverse( $below_sizes );
+
+		$below_sizes[] = array(
+			'name' => __( 'Medium', 'gutenberg' ),
+			'slug' => 50,
+			'size' => $spacing_scale['mediumStep'] . $spacing_scale['units'],
+		);
+
+		$current_step = $spacing_scale['mediumStep'];
+		$x_count      = null;
+		$above_sizes  = array();
+		for ( $x = $steps_mid_point + 1; $x < $spacing_scale['steps']; $x++ ) {
+			$current_step = '+' === $spacing_scale['operator']
+				? $current_step + $spacing_scale['increment']
+				: $current_step * $spacing_scale['increment'];
+
+			$above_sizes[] = array(
+				/* translators: %s: Muliple of t-shirt sizing, eg. 2X-Large */
+				'name' => $x === $steps_mid_point + 1 ? __( 'Large', 'gutenberg' ) : sprintf( __( '%sX-Large', 'gutenberg' ), strval( $x_count ) ),
+				'slug' => $x * 10,
+				'size' => round( $current_step, 2 ) . $spacing_scale['units'],
+			);
+
+			if ( $x === $steps_mid_point + 2 ) {
+				$x_count = 2;
+			}
+			if ( $x > $steps_mid_point + 2 ) {
+				$x_count++;
+			}
+		}
+
+		_wp_array_set( $this->theme_json, array( 'settings', 'spacing', 'spacingSizes', 'default' ), array_merge( $below_sizes, $above_sizes ) );
+	}
+
+	/**
+	 * Merge new incoming data.
+	 *
+	 * @param WP_Theme_JSON $incoming Data to merge.
+	 */
+	public function merge( $incoming ) {
+		$incoming_data    = $incoming->get_raw_data();
+		$this->theme_json = array_replace_recursive( $this->theme_json, $incoming_data );
+
+		/*
+		 * The array_replace_recursive algorithm merges at the leaf level,
+		 * but we don't want leaf arrays to be merged, so we overwrite it.
+		 *
+		 * For leaf values that are sequential arrays it will use the numeric indexes for replacement.
+		 * We rather replace the existing with the incoming value, if it exists.
+		 * This is the case of spacing.units.
+		 *
+		 * For leaf values that are associative arrays it will merge them as expected.
+		 * This is also not the behavior we want for the current associative arrays (presets).
+		 * We rather replace the existing with the incoming value, if it exists.
+		 * This happens, for example, when we merge data from theme.json upon existing
+		 * theme supports or when we merge anything coming from the same source twice.
+		 * This is the case of color.palette, color.gradients, color.duotone,
+		 * typography.fontSizes, or typography.fontFamilies.
+		 *
+		 * Additionally, for some preset types, we also want to make sure the
+		 * values they introduce don't conflict with default values. We do so
+		 * by checking the incoming slugs for theme presets and compare them
+		 * with the equivalent default presets: if a slug is present as a default
+		 * we remove it from the theme presets.
+		 */
+		$nodes        = static::get_setting_nodes( $incoming_data );
+		$slugs_global = static::get_default_slugs( $this->theme_json, array( 'settings' ) );
+		foreach ( $nodes as $node ) {
+			$slugs_node = static::get_default_slugs( $this->theme_json, $node['path'] );
+			$slugs      = array_merge_recursive( $slugs_global, $slugs_node );
+
+			// Replace the spacing.units.
+			$path    = array_merge( $node['path'], array( 'spacing', 'units' ) );
+			$content = _wp_array_get( $incoming_data, $path, null );
+			if ( isset( $content ) ) {
+				_wp_array_set( $this->theme_json, $path, $content );
+			}
+
+			// Replace the presets.
+			foreach ( static::PRESETS_METADATA as $preset ) {
+				$override_preset = ! static::get_metadata_boolean( $this->theme_json['settings'], $preset['prevent_override'], true );
+
+				foreach ( static::VALID_ORIGINS as $origin ) {
+					$base_path = array_merge( $node['path'], $preset['path'] );
+					$path      = array_merge( $base_path, array( $origin ) );
+					$content   = _wp_array_get( $incoming_data, $path, null );
+					if ( ! isset( $content ) ) {
+						continue;
+					}
+
+					if ( 'theme' === $origin && $preset['use_default_names'] ) {
+						foreach ( $content as &$item ) {
+							if ( ! array_key_exists( 'name', $item ) ) {
+								$name = static::get_name_from_defaults( $item['slug'], $base_path );
+								if ( null !== $name ) {
+									$item['name'] = $name;
+								}
+							}
+						}
+					}
+
+					if (
+						( 'theme' !== $origin ) ||
+						( 'theme' === $origin && $override_preset )
+					) {
+						_wp_array_set( $this->theme_json, $path, $content );
+					} else {
+						$slugs_for_preset = _wp_array_get( $slugs, $preset['path'], array() );
+						$content          = static::filter_slugs( $content, $slugs_for_preset );
+						_wp_array_set( $this->theme_json, $path, $content );
+					}
+				}
+			}
+		}
+	}
 }
diff --git a/lib/compat/wordpress-6.1/class-wp-theme-json-resolver-6-1.php b/lib/compat/wordpress-6.1/class-wp-theme-json-resolver-6-1.php
index 58abcc27c04ec5..efb2025d6f4ddb 100644
--- a/lib/compat/wordpress-6.1/class-wp-theme-json-resolver-6-1.php
+++ b/lib/compat/wordpress-6.1/class-wp-theme-json-resolver-6-1.php
@@ -16,6 +16,25 @@
  * @access private
  */
 class WP_Theme_JSON_Resolver_6_1 extends WP_Theme_JSON_Resolver_6_0 {
+	/**
+	 * Given a theme.json structure modifies it in place
+	 * to update certain values by its translated strings
+	 * according to the language set by the user.
+	 *
+	 * @param array  $theme_json The theme.json to translate.
+	 * @param string $domain     Optional. Text domain. Unique identifier for retrieving translated strings.
+	 *                           Default 'default'.
+	 * @return array Returns the modified $theme_json_structure.
+	 */
+	protected static function translate( $theme_json, $domain = 'default' ) {
+		if ( null === static::$i18n_schema ) {
+			$i18n_schema         = wp_json_file_decode( __DIR__ . '/theme-i18n.json' );
+			static::$i18n_schema = null === $i18n_schema ? array() : $i18n_schema;
+		}
+
+		return translate_settings_using_i18n_schema( static::$i18n_schema, $theme_json, $domain );
+	}
+
 	/**
 	 * Return core's origin config.
 	 *
diff --git a/lib/compat/wordpress-6.1/theme-i18n.json b/lib/compat/wordpress-6.1/theme-i18n.json
new file mode 100644
index 00000000000000..469783409c891c
--- /dev/null
+++ b/lib/compat/wordpress-6.1/theme-i18n.json
@@ -0,0 +1,86 @@
+{
+	"title": "Style variation name",
+	"settings": {
+		"typography": {
+			"fontSizes": [
+				{
+					"name": "Font size name"
+				}
+			],
+			"fontFamilies": [
+				{
+					"name": "Font family name"
+				}
+			]
+		},
+		"color": {
+			"palette": [
+				{
+					"name": "Color name"
+				}
+			],
+			"gradients": [
+				{
+					"name": "Gradient name"
+				}
+			],
+			"duotone": [
+				{
+					"name": "Duotone name"
+				}
+			]
+		},
+		"spacing": {
+			"spacingSizes": [
+				{
+					"name": "Space size name"
+				}
+			]
+		},
+		"blocks": {
+			"*": {
+				"typography": {
+					"fontSizes": [
+						{
+							"name": "Font size name"
+						}
+					],
+					"fontFamilies": [
+						{
+							"name": "Font family name"
+						}
+					]
+				},
+				"color": {
+					"palette": [
+						{
+							"name": "Color name"
+						}
+					],
+					"gradients": [
+						{
+							"name": "Gradient name"
+						}
+					]
+				},
+				"spacing": {
+					"spacingSizes": [
+						{
+							"name": "Space size name"
+						}
+					]
+				}
+			}
+		}
+	},
+	"customTemplates": [
+		{
+			"title": "Custom template name"
+		}
+	],
+	"templateParts": [
+		{
+			"title": "Template part name"
+		}
+	]
+}
diff --git a/lib/compat/wordpress-6.1/theme.json b/lib/compat/wordpress-6.1/theme.json
index 00acba508d0336..9c5bd2886b2560 100644
--- a/lib/compat/wordpress-6.1/theme.json
+++ b/lib/compat/wordpress-6.1/theme.json
@@ -189,7 +189,15 @@
 			"blockGap": null,
 			"margin": false,
 			"padding": false,
-			"units": [ "px", "em", "rem", "vh", "vw", "%" ]
+			"customSpacingSizes": true,
+			"units": [ "px", "em", "rem", "vh", "vw", "%" ],
+			"spacingScale": {
+				"operator": "*",
+				"increment": 1.5,
+				"steps": 10,
+				"mediumStep": 1.5,
+				"units": "rem"
+			}
 		},
 		"typography": {
 			"customFontSize": true,
diff --git a/lib/experimental/class-wp-rest-block-editor-settings-controller.php b/lib/experimental/class-wp-rest-block-editor-settings-controller.php
index 0d1aa47fb2b02b..d9b726f1158da2 100644
--- a/lib/experimental/class-wp-rest-block-editor-settings-controller.php
+++ b/lib/experimental/class-wp-rest-block-editor-settings-controller.php
@@ -275,6 +275,16 @@ public function get_item_schema() {
 					'type'        => 'array',
 					'context'     => array( 'post-editor', 'site-editor', 'widgets-editor' ),
 				),
+				'spacingSizes'                           => array(
+					'description' => __( 'Active theme spacing sizes.', 'gutenberg' ),
+					'type'        => 'array',
+					'context'     => array( 'post-editor', 'site-editor', 'widgets-editor' ),
+				),
+				'spacingScale'                           => array(
+					'description' => __( 'Active theme spacing scale.', 'gutenberg' ),
+					'type'        => 'array',
+					'context'     => array( 'post-editor', 'site-editor', 'widgets-editor' ),
+				),
 			),
 		);
 
diff --git a/lib/experimental/class-wp-theme-json-resolver-gutenberg.php b/lib/experimental/class-wp-theme-json-resolver-gutenberg.php
index 6c4e5b534a4f78..ad6f4b9942dfa2 100644
--- a/lib/experimental/class-wp-theme-json-resolver-gutenberg.php
+++ b/lib/experimental/class-wp-theme-json-resolver-gutenberg.php
@@ -173,6 +173,8 @@ public static function get_merged_data( $origin = 'custom' ) {
 		if ( 'custom' === $origin ) {
 			$result->merge( static::get_user_data() );
 		}
+		// Generate the default spacing sizes presets.
+		$result->get_spacing_sizes();
 
 		return $result;
 	}
diff --git a/lib/load.php b/lib/load.php
index d76ec3181b7cfe..8c77ab5ee0ba43 100644
--- a/lib/load.php
+++ b/lib/load.php
@@ -124,6 +124,7 @@ function gutenberg_is_experiment_enabled( $name ) {
 
 // WordPress 6.1 compat.
 require __DIR__ . '/compat/wordpress-6.1/blocks.php';
+require __DIR__ . '/compat/wordpress-6.1/block-editor-settings.php';
 require __DIR__ . '/compat/wordpress-6.1/persisted-preferences.php';
 require __DIR__ . '/compat/wordpress-6.1/get-global-styles-and-settings.php';
 require __DIR__ . '/compat/wordpress-6.1/class-wp-theme-json-6-1.php';
diff --git a/schemas/json/theme.json b/schemas/json/theme.json
index 75e346e0982f5b..be7ceb3433f028 100644
--- a/schemas/json/theme.json
+++ b/schemas/json/theme.json
@@ -226,6 +226,69 @@
 								"type": "string"
 							},
 							"default": [ "px", "em", "rem", "vh", "vw", "%" ]
+						},
+						"customSpacingSize": {
+							"description": "Allow users to set custom space sizes.",
+							"type": "boolean",
+							"default": true
+						},
+						"spacingSizes": {
+							"description": "Space size presets for the space size selector.\nGenerates a custom property (`--wp--preset--space-size--{slug}`) per preset value.",
+							"type": "array",
+							"items": {
+								"type": "object",
+								"properties": {
+									"name": {
+										"description": "Name of the space size preset, translatable.",
+										"type": "string"
+									},
+									"slug": {
+										"description": "Kebab-case unique identifier for the space size preset.",
+										"type": "string"
+									},
+									"size": {
+										"description": "CSS space-size value, including units.",
+										"type": "string"
+									}
+								},
+								"additionalProperties": false
+							}
+						},
+						"spacingScale": {
+							"description": "Space size presets for the space size selector.\nGenerates a custom property (`--wp--preset--space-size--{slug}`) per preset value.",
+							"type": "object",
+							"properties": {
+								"operator": {
+									"description": "With + or * depending on whether scale is generated by increment or mulitplier.",
+									"type": "string",
+									"enum": [ "+", "*" ]
+								},
+								"increment": {
+									"description": "The amount to increment each step by.",
+									"type": "number"
+								},
+								"steps": {
+									"description": "Number of steps to generate in scale.",
+									"type": "integer"
+								},
+								"mediumStep": {
+									"description": "The value to medium setting in the scale.",
+									"type": "number"
+								},
+								"units": {
+									"description": "Units that the scale uses, eg. rem, em, px.",
+									"type": "string",
+									"enum": [
+										"px",
+										"em",
+										"rem",
+										"vh",
+										"vw",
+										"%"
+									]
+								}
+							},
+							"additionalProperties": false
 						}
 					},
 					"additionalProperties": false