From what I hear, if anything, T will do the opposite of help you lose weight because your appetite goes up. So you have to be committed to working out to gain the muscle to improve the metabolism to deal with the appetite. The best way to do that is start before T because you're going to be dealing with a ton of other stuff at the time. 2nd puberty...ewwww!!! We all know how icky 1st puberty was! Self esteem could go down with potential acne too, so you want to be in a good motivation to workout BEFORE that all starts imo. And your face is more likely to change because of a difference in fat distribution, than any bone changes, although there can be some bone changes if you're younger. Initially you do often get that puffy face though, and as soon as some go on T it seems they can find it harder to pass just because of the temporary issue! So yeah, with all that going on, if you want to lose weight on T, you need to put the effort in before T so it's more 2nd nature to train and not something you have to force yourself to go through when you might be feeling a little down. And exercise is the best thing for those moments because it's a natural high, but the last thing we often feel like doing, especially if we're not used to it.
It's a 2nd puberty and a potential hard couple of months to start with. Add in increased appetite and T isn't going to help with weight loss at all.