Setup vclusters from an existing cluster, and make a kubeconfig file for access. The Kubernetes api will be accessible via nodeport, which means the node IP must be a static/reserved IP (otherwise it may randomly change and invalidate the config).
vcluster-setup <vcluster name>
The kubeconfig file generates in output/kubeconfig.yaml.
Test the kubeconfig file:
kubectl --kubeconfig output/kubeconfig.yaml get namespaces
Source: https://www.vcluster.com/docs/using-vclusters/access#via-nodeport-service
The link does not tell you how to use the port; you have to add it to the kubeconfig after retrieving it.