Building in map editor, not to have at the start but to plan around buildings

So I've seen a few things close to what I was thinking about but the buildings in the map editor is the closest. So say I wanna tailor some terrain to the building most notably the smallest map size, there's not a lot of room to work with and I can pretend it was an old settlement of beavers that moved on after a while in the area, or something and they would have done the landscaping. My only current solution is a second monitor doing wiki things for building sizes, if it's even accurate with the recent changes I've been watching Real Civil Engineer on youtube playing through the changes.