Thanks for the answer, but I was not looking for cluster linking.
I have received an answer from support which I want to share:
I confirm that in the same Confluent Cloud organization it’s possible to deploy different types of clusters (Basic, Standard, Dedicated) with different types of networking options; so you can have a mix of public and private endpoints clusters, since each cluster will resides in its own VPC.
I also confirm that the network configuration cannot be switched on a cloud cluster.