I think some cosmetic surgeons will do breast augmentation with just informed consent. I suspect more involved procedures such as FFS and GCS would require a therapist’s letter.
My endo is very flexible. She’ll prescribe any hormonal Rx that’s medically safe and effective. She’s good about explaining the pros/cons of various therapies, and suggesting what she feels is the best choice given my progress and circumstances. But she’ll prescribe something I want to try if it isn’t risky. For example, I told her I might want to switch to patches if I progress too fast on injections. She’s okay with that.
So I think it really depends on the doc. A lot of them are pretty rigid and have a “one size fits all” approach to HRT. I’d stay away from them if at all possible. But the more informed docs are more willing to work with their patients to create a plan that’s tailored to their needs.