Hide landscape foliage/grass where an actor is placed?

No, but to do that you run the same texture in world space into the foliage as the value for Opacity.

If you put time into the shader you can make it so that it only samples the exact point at the object’s pivot, so that the whole plant goes away when appropriate instead of partially disappearing.

Samething thing for grass - mostly because its painted in as foliage in like 99% of projects anyway, but even those using grass nodes are better off handing it that way instead of messing with extra landscape paint layers.

Partially because before you hide it you probably want to do other things to it, like move it around or make it bend…