Hello all, is it difficult to turn a rke2 from single server to HA? I can set 3 replicas on the first server and then add the other to control planes later on?

Rke2 always uses embedded etcd so yeah you can add servers whenever

So when I deploy rancher I can set the replicas to 3 and it will auto adjust when the other control planes are added

Well the extra ones may remain unscheduled until you add more nodes, depending on how the pod is set up.