In this video, we’ll be covering how to add a Collision Manager to your scene so that your Flesh Asset can collide with other Rigid Body Actors of your choosing. By default, collisions are only enabled for the Floor Actor by the Deformable Solver.
https://dev.epicgames.com/community/learning/tutorials/l05X0/fortnite-fab-unreal-engine-5-8-chaos-flesh-and-soft-body-physics-part-2-collisions-beginners-tutorial