The MDM Data Model is different for each organization. Even if someone provided you with "a" data model, chances are very low that it would align with your client's model. The person you need to be asking is the client. You must use their data model for your POC to have any meaning. Ask who is the architect who designed their data model. Ask who maintains their data model. Talk to your client.
You can export Schema Viewer and filter out columns name and export as JPG file and you will get bird eye of the data model and then you can narrow as per your need.