I'm not too sure what you mean exactly. The only thing this plugin does with regionIds is changes them. Everything else is decided based on x,y coordinates. You can change specific tiles, or you can change areas of tiles, or you can change areas of tiles using map prefabs (the easiest and my favorite way). So essentially if you wanted an entire area changed it would be easy to set up a prefab of it on a TileMap (another map similar to spawn maps in an event spawner) then when you want to switch you just do a usePrefab call to it and it'll switch out the tiles on the game map with the tiles from the other map. If you meant changing all regionIds on the map to another Id that can be done with a simple loop. Loop through every tile on the map and check the regionId if it matches the requested Id then changeRegionId to whatever new value.

Once I'm fully finished with both versions I plan on doing little tutorial videos showing how to use the different features of this plugin. I've grown to love the extra freedom this plugin provides when mapping and will be using this in my own game(s) without a doubt.

Btw I'm really close to wrapping up the MV version of this plugin, I found compatibility with Altimit Pixel Movement on MV although it requires a small edit to the Altimit Pixel Movement plugin to work. (These two plugins were completely incompatible until this fix, due to how Altimit movement gathers tile data and reads from that data, I had to update that plugins tile data which was stored in memory whenever tiles changed due to MapTransform plugin). I also went ahead and made this plugin compatible with QMovement as well, very similar fix was required there as well but this QMovement fix was able to be done entirely within the MapTransform plugin file.