Is there any way to create invisible barriers or to limit the height of a room? I'm trying to simulate my apartment, but 128 blocks is too big and the walls I create prevent a clear view of the player.

up

The only way to do that is to toggle some kind of trigger to show up walls at some point like going up to stairs, though it can't be hidden...

You can adjust the x and y dimensions, but for z levels there isn't anything implemented yet. What you can do to limit it is to elevate your entire construct by placing blocks underneath.