A CRDT requires its own data model that becomes, in a sense, the "main" data model. Because its design and constraints effectively become the design and constraints and requirements on the downstream data snapshot.

CRDT's generally require you to track a lot more stuff in your snapshot model than you would otherwise, in order to create messages that contain enough information to be applied and resolved.

E.g. what was previously an ordered list of items without ID's may now need to become a chain of items each with their own ID, so you can record an insert between two other items rather then just update the list object directly.

So yes, the CRDT is effectively your data model.