The manufacturers all vary so much

I have cob and full bridles from different companies that are the same size and pony and cob bridles that are interchangeable
I think you'd be better getting a made to measure and they aren't that expensive, I have a web address somewhere that I'll hunt out if you're interested.
You may find you need to make a bridle from parts even if you do not go made to measure. Spirit has a cob bridle with full size browband and Whisper a pony bridle with a cob browband. Good luck