I am not a doctor..
As far as I'm aware, puberty blockers are essentially useless after puberty has finished.. So, no, they won't prescribe them at that point. As for the effects of T, you get what you get, it's not something you have a huge amount of control over. Low doses may slow down changes, but in the end, you will end up with whatever changes you were going to get regardless of dose.
Estrogen blockers come with their own issues, like, you can't exist long term without some kind of sex hormone active in your system, it results in some serious issues.
Short version? You get what you get, you don't get to pick and choose.