Comms plan templates

Yes you are right, these are scenario-based materials.  This is Microsoft's suggested way of tackling adoption, using 6 core scenarios, that tally with the productivity library materials.

Outside of this there is a mix of resources available, some of which go back a few years, a more recent one though is https://www.microsoft.com/en-us/download/details.aspx?id=54633. 

If you go through the https://fto365dev.blob.core.windows.net/media/Default/DocResources/en-us/Microsoft%20365%20User%20Adoption%20Guide.pdf, if you haven't already, check the various resources for ideas.