I'm going to be watching this thread because my 6'4" 230 pound son-in-law has asked me to make him a quilted jacket. I googled it and yes, young guys are wearing them.
I got a book from the library, "Reclaimed Quilts " by Kathleen McVeigh and Dale Donaldson. They talk specifically about using vintage quilts to make garments but have instructions for construction, including for their "Jules Chore Coat" with a scannable link to download the pattern for free.
I've seen a couple of YouTube videos with tips on constructing quilted coats too so you might find some help there