Okay the argument 'well you can't smoke, you can't get a tattoo, etc until 18' is bullshit. Those things are not medical.

You know what I was able to get before 18

Birth control.

You know what you can do under 18 in Tennessee. Get married. Have a child.

https://www.npr.org/2024/12/04/nx-s1-5179003/supreme-court-gender-affirming-care-trans-kids