It's true that you can't reduce the size of your shoulder bones.
However, your shoulders are more than just bones, they are flesh and muscle too.
My biceps over time have shrunk quite a bit.
How much my back and chest muscles have shrunk is harder to tell.
I just wore a blouse that used to be tight on the shoulders a year ago and now it fits perfectly.
No, you can't expect anything that's physically impossible, but HRT will be an improvement.
Yes, it is great to be in the supermarket and have the little old ladies say,
"You're such a tall girl, could you get that off the top shelf for me?"