How do I make it so that the player sprite can fall into the Top-Down trench hole? (2.5D)

Hello

I've just started using Construct 3 for a game project. It's an ATARI-2600 styled war game with a Top Down perspective, hence it includes trench lines that you can go inside and outside of. I'm tryna make it so that when the player / NPCs reach the hole, it falls into the trench floor to give an illusion of depth in a 2D environment. I also wanna make ladders to make them be able to climb out of the trenches.