In theory, I believe you should have the right to do whatever you want with your body. Even if others think it's a bad idea. Even if it IS a bad idea. Get whatever tattoos you want, where you want, piercings, hair shavings, any body mod, without fear of arrest. I don't think that means society should never judge your choices. The easiest example I can think of is Nazi tattoos on your face. Can't get a job? Tough. That said, I do think society should be open-minded, and know bigotry when you see it.
So would this include transgender surgeries and hormones? Well....in theory, yes. But I do not think the doctor has the right to perform any surgery he wants, or prescribe anything he wants, based on the request of the patient alone. Even if that patient is in distress and desperate for these treatments.
These treatments have a high complication rate that would be considered unacceptable for any other purpose besides dysphoria. Doctors are expected to perform quality surgeries that produce excellent results. They are expected to prescribe medications that produce excellent results with a minimum of negative side effects. The only exception to the rule is if the patient's body is dying due to some catastrophic circumstance. (Not "I'll kill myself if you don't treat me!").
Doctors are also expected to perform the least invasive treatments possible. They are not supposed to up-sell their patients into more elaborate, complicated, expensive treatments they could do without.
The trouble with "informed consent" is that the criterion for it is only a document, with a list of possible outcomes. I've read some of the forms- they are full of jargon that most lay people wouldn't know, and teenagers certainly wouldn't understand. It's hard to explain to even a mature person what living with a disability is like when they themselves haven't lived it. It's impossible to get a teenager to fathom what it's like. They can't understand how dealing with chronic side effects, that pile on as the years go by, will be like. So in a way, there really is no informed consent. It's like pregnancy- no, you don't know how you will feel during pregnancy until you are pregnant.
And I seriously doubt these doctors take the time to get graphic about what early onset dementia looks like. I doubt they show pictures of necrosis.