best size LUN with SRM Array Based

I am installing a new infrastructure vmware (1 VCSA + 4 esxi 6.5)  I have a VNX storage in SAN, at the end i need to implement SRM for DR for about 15 VM, in array-based (with recoverpoint) now my doubt is how to design Datastore, i would like to create 2 Datastore Cluster
- Datastore Cluster not replicated with 3 LUNs of 2 TB
- Replicated Datastore Cluster with 3 LUNs of 1 TB or 1 LUN of 3 TB

I would not want to create too big LUN because I can not add VMs that I can not replicate.
Or what a different solution?