More modern methods now, you can still do a 1 off fit but they just go off of measurements. They'll also do a fit consultation based off your other boots or send you a try on pair.

True story, I was at the lake and my son dropped a 500$ rod and reel setup off the boat. I dove in and got it but got my shirt covered in mud and moss. So when I got back to the marina I had my shirt off and went in to buy a shirt, but they wouldn't let me in without a shirt. So I made them bring me one outside to try on and then went in to pay for it...