No one size fits all. If QMK RC doesn't recognize a built-in command, it (in a fashion similar to QMK itself), calls a user function:
__attribute__((weak)) void qmk_rc_process_command_user(qmk_rc_command_t* command) { }
And so, if you wanted to re-implement the OLED_OFF
command, you could write:
#define MY_OLED_OFF 128
void qmk_rc_process_command_user(qmk_rc_command_t* command) {
switch (command->id) {
case MY_OLED_OFF: oled_off(); break;
}
}