Not on HRT, but I went through a bodybuilding phase when I was in denial. Don't get your hopes up too high on gaining muscle mass, not all cis-males can make noticeable gains in mass, even after years in the gym, trying every workout routine possible. I made some gains in strength, and really modest gains in mass, some in areas I wish I hadn't, some I'm delighted in. Decline press works lower pecs, Chest flyes work cleavage. I made a real mistake overworking hip adductors. Gaining muscle mass there, which I really did somehow to the point I was lifting the whole stack easily, means if you later gain fat, your legs rub together in normal walking. Anyone reading this, don't do this. But the area I wanted at the time to get bigger, my shoulders, not even a strength change, after years in the gym, main reason I did decline and flyes, I can't bench press because basically have no shoulder muscles.