My crowntail male always has that look./...Not SBD, just a rounder/boxy belly. You'll find that younger bettas (breeders bettas) tend to have a rounder belly because they are fed more. For the pictures on google, take in mind some of those bettas belong/ed to people who just overfeed.... Or use the instructions on the bottle of food x.x
Mine don't get round bellies, except the youngin', females I am conditioning are a bit more fed, same with conditioned males, and greedy bettas of course
I watched my baby take the biggest bloodworm and take off
There is a difference however, with a "full belly" and a "bloated belly". Bloated can cause SBD, which is why many recommend pellets VS flakes because it is easier to monitor the amount fed.