Kubernetes api-server command inaccessible?

Question

1. I am trying to access kube-apiserver api.
2. I wish to feed it with a file using --admission-control-config-file flag, to enforce "baseline" Pod Security Standard.
3. I want to add admission controllers
4. Is it possible to create custom policy for admission controllers?

I ran kubectl get pods --n kube-system followed by kubectl describe pod/kube-apiserver-test-control-plane -n kube-system and I can see "Commands: kube-apiserver", but I am not sure what I can do with that.

Thanks!