Doc link: https://docs.openshift.com/container-platform/4.17/scalability_and_performance/recommended-performance-scale-practices/recommended-etcd-practices.html#etcd-node-scaling_recommended-etcd-practices

In this documentation, we explain that we can scale up the control plane from 3 nodes to 4 or 5. However, we should make a clearer statement that clusters must always be installed with 3 control plane replicas and then scaled up as a day-2 operation, i.e. that we cannot install OpenShift with 5 replicas from the beginning.