The game has a couple special tags to help with mapping

The penetrable tag allows for anything that has the tag to be shot through, can go through up to 32 things. Useful for situations where you might have a thin wall or weak cover like a piece of plywood. Should be used sparingly.

To apply simply add the tag to anything like a prop_static or func_brush. Make sure you click the green plus button to add the tag

corpse - for corpse only on trigger

debris

carriable - only equipment