How many Control Plane I will get if I select only 1 zone or 4 zones in Regional GKE cluster respectively?

Solution 1:

Control plane runs on a master node that is not visible for GKE users since it's a manged service. All the worker nodes can talk to it using Kubernetes API calls via a single unified endpoint - despite how many zone the they are in.

So - technically - you will get one master node / control plane per zone. However they will be available via one endpoint.

Documentation doesn't say it directly but you're getting a control plane's replica for every zone - which means you get as many replicas a the zones you're using. However it's just a replica and they work as a backup in case of failure:

The control plane is replicated across three zones of a region. For node pools, you can manually specify the zone(s) in which the cluster's node pools run or you can use the default configuration, which replicates each node pool across three zones of the control plane's region. All zones must be within the same region as the cluster's control plane.

You can also have a look at this answer which may give you some insigt.