Plastic dry cleaner sheets/garmet bag on top and bottom. Lay flat, then fold. The plastic keeps from wrinkling. We packed for 2 weeks in a carry on to Italy this way.

https://www.amazon.com/dp/B0BWXYXXG1

I wouldn’t even try. Just fold it in a way that the shoulders can stay flat and tell him to send to dry cleaners

You can get a garment mailer box. Tell your son to have the suit pressed upon arrival.

include a steamer. Fold it with towels between the folds.

I need to mail a suit to my son at college. What is the best way to do this so that it isn’t a wrinkled mess on arrival?