How to add physics component to character blueprint ? UE4

If you’re using a Character class object, then it can’t do full simulation, because Character has its own forward-kinematic simulation to handle “gameplay movement” which is non-physical.
The Character can collide with other objects, though, so you could add collider objects that push other things out of the way.

If you had more details about what specifically you want the simulation to do, perhaps someone can give a better answer for how to accomplish that.