Sometimes it doesn't. I'm 12 years on T next week and I'm still dummy thicc lol. It'll happen, maybe just not 100% how you want or expect, if you're not careful you'll get a beer gut too. That's one of those things that changes slowly and you don't really notice except when you think about it and you realize it's definitely happened and maybe not always in ways you're completely thrilled with, it's kinda like when you realize you now have ass hair. Gaining and losing weight can make it visibly happen faster, along with working out - but work out for the health benefits, not for the hope it'll make you less thicc because many times it won't do that but the new ability to crush watermelons with your thighs is pretty fun.