There a few things that will help you to fit a particular Shotgun ( or rifle for that matter )
Trigger pull ( or length of pull ), determine which eye is Eye dominate , drop at cheek or comb and Butt Plate shapes & or angle and amount of drop.
You can just take for granite, the average shotgun for the masses is a compromise...I:E that Stoeger SxS
These shotguns are designed for a right-handed male of average height , with a 33-inch arm length.
You can adjust the length of pull and even the butt plate angle with these, though
Little, short of a re-stocking will change amount of drop cheek or comb.
Nor will it be a perfect fit if you are a Lefty.
Frankly, they are just fine for static distances in CAS, here you will not need custom fitted Trap shotguns.
The best way is measure your own length of pull and adjust angle fit at the shoulder by
Contacting qualified gunsmith for a "TRY GUN" .
The try gun will determine your length of pull, stock drop and other measurements that may help you find that best fit.