Rotating an object on 3D Space based on 2D data

I am trying to make my game object look at my touch position. Best method that came to my mind was that to simply taking the touch position data from Unity's Input system.

Heres where I stuck at; touch position is 2D space as expected but I need a Z axis to be able to rotate it properly in 3D space.

Any idea on how to find a solution for this issue?

         if(Input.touchCount > 0)
         {
             Touch touch = Input.GetTouch(0);
             Vector3 touchPos = touch.position;
             Debug.Log(touchPos);
             transform.LookAt(touchPos);
         }