Render Overhead objects separately

For features such as the overhead tiles feature of Foundry. This would be applied to a building roof or treetops, and can be hidden or manipulated to simulate a character walking under them.

Some assets would need to be modified, e.g. when I do this in FoundryVTT, I use a tree stump asset on the ground level, then treetop at a height above it. Character tokens can be under or over the treetop depending on their elevation.
For details, look at the Levels module for Foundry.