There are sevaral great polishes out there.
I have a system I created sevaral decades ago that works well for me for the paints I use including urethane paints.
I use a product made by Novus. They make a #1, #2, and #3. I use the #2 almost exclusively followed up by an automotive product made by 3M called Finesse-it ll Finishing Material. It comes in quarts and works incredibly - BUT it is spendy. I bought mine 12-14 years ago and was $30.00, BUT now is $75.00 to $100.00 so if $$$$ is an issue.......
Lastly I use Meguiar's #7 Show Car Glaze which is a super-fine polish/wax, and gives a mirror like finish.
Hope all that helps
I love Mecum Auctions and Barrett/Jackson auctions.
I bought all the model stuff I wanted for Christmas because no one else would spend that much on me