Help with ways to get Tilemap layout to another Tilemap

Godot Version

4.2.1.stable.mono

Question

Hi, I am trying to make a prototype that generates a level from a set of dungeon like rooms in 2D. I want to have pre made rooms to generate the level from but I am struggling on how to go about it.

Making rooms like scenes with a tilemap each that I instantiate seems wrong, making a level have numerous tilemaps. But I have not found a way to copy layout information from a tilemap and paste it to another either.

Another possibility is to use patterns but to make a room with more layers then one will require a pattern for each layer making it hard to organize and will require some way to keep all patterns the same size to stack properly.

Does anyone know if I have missed something or can give me a tips on how to approach this problem?

Thanks!
//Alex