The Renegade website has instructions on how to measure your hoof, and I expect that they would allow exchanges if you got the measurement wrong.
But the Renegades will only work if you have a horse with a well-established “barefoot performance trim,” meaning that the heels are well back, the toe is back and short, and there is no flaring in the hoof wall. If the heels are underrun or the toe is slipping forward, the Renegades will not fit. And if there is flare, the boots will pop off.
It’s a small company, and they have good customer service, and a Facebook group you can join to ask questions. You could post photos of your horse’s feet and ask if he could wear Renegades at this point.
I am on my second pair (we wore the first pair out on gravel trails), and have never had a rub with them. I would absolutely recommend them if your horse has a good barefoot trim. If not, other brands would be more suitable.
When I got my first pair, I had to wait through the winter to grow out some damage and flaring from the previous summer.
You can also ask the company if someone in your region is a distributor. For instance my vet (who is also trained as a farrier) sells them, but doesn’t advertise the fact as far as I can tell. I think they are sold more by hoof care practitioners, not in tack stores.