Figure out the number of read-write nodes and read nodes required for a production

I have a use case to identify the number of nodes (writer and read replicas) required to set up a causal cluster based on the file size or number of nodes/relationships. Is there any way to formulate something in such a way that we can identify the number of nodes required in causal cluster based on our files / nodes-relationships in a file?

in a causal cluster regardless of number of nodes/relationships in the graph, the entire graph is replicated to each of the other cluster members. Further there is generally 1 Leader cluster member which is capable of WRITES and all others are Followers/READ-REPLICAS which allow READS. You can not perform a WRITE on a Follower/READ-REPLICA