Is there a way to make different layers apply to tilemap layers

Say for instance, if I wanted to have a multiply layer apply to all the tiles placed on a tilemap layer below it? I’m currently having trouble as I have made a tilemap layer and placed tiles around but I would like to do some non destructive layers overtop and apply some shading. If I make another tilemap for the multiply layer I sometimes erase both layers. Plus I have to re place all of the tiles I placed previously. It’s kind of confusing

I consider developers should implement Merge down of any layers of to any layers with Mode applying even for Indexed sprites (and fix Mode not applyed over transparent pixels for RGB sprites). It already works when you do Flatten or Flatten Visible, but only for RGB and it’s really weird way.

Any normal layer to Tilemap layer and any Tilemap layer to normal layer (by auto converting to image). Except for Reference layers, of course.

If two Tilemap layers match tiles size and offset it will automatically give us merged tileset.