Polishing Paint

I would do A small section of dull area first.
Wouldn't even wetsand to start. You don't know how much paint material is there. Use a medium cut buff compound at most.
Do a 1 foot by 2 foot flat area first. If you don't have experience with
A real buffing machine, have someone do it who does.
They will know after 2 minutes if that finish will shine and be
Acceptable.you will know in a hurry if buffer starts to remove paint through to sealer or primer.
You could certainly try to do by hand but takes forever.

Good luck