Tracking Mesh Warp effect to the video

Mesh Warp has no properties that will take expressions or accept X or Y position properties. Your only option would be to motion track the part of the video you want to warp, motion stabilize it so that it doesn't move, Create a copy, do some masking, do the warping, then pre-compost the motion-stabilized and masked warp, then put the motion back in the two copies of the shot, the original, and the pre-composed masked, and warped section.

There are other distortion effects. It might be simpler to create the composite using other effects. We need to see what you are trying to do to give you much more help. Run the distortion you want on a frame of your footage and post a screenshot. Maybe we can come up with an easier solution.