I haven’t used Paper2d much, but you should be able to make a box that is a component of your player and enemy characters directly in the blueprint component screen. One way I solved this same problem ages ago with a platforming game I did was that I put an invisible collision box at the feet of the player that killed enemies when it collided with them. It was a kind of sloppy solution though, as it meant if you were moving fast enough horizontally or hit it at just the right angle, you could kill enemies without actually having hit the top of them. The raytracing used in my proposed solution is supposed to fix this issue by making sure that the enemy is indeed below the player.