It absolutely is not. Children cannot consent to sterilizing medical procedures. Doctors are prohibited by law from performing tubal ligations on women under 18, and most won’t do it on women under 30.
The science on trans youth is evolving rapidly; the UK, Sweden, and Finland just severely curtailed use of blockers and hormones on minors due to the clear risks of harm and unclear risks of benefit. I expect the US to follow suit in a few years, once our current political fever breaks and the medical evidence remains. The Society for Evidence-Based Gender Medicine is a good place to review the science and track new developments:
Linking an anti-trans organisation, nice [1]
If your gender dysphoria is destroying your mental health and your parents will send you to torture camp for being on hormones, then taking hormones in secret is the moral thing to do.
Doctors not performing tubal ligations on women and other afab people under 30 is pure, unadulterated misogyny.
edit: responding to post by deepdriver below, SEGM is a torture-promoting group (yes, conversion therapy is torture) funded by dark money. https://transsafety.network/posts/segm-uncovered/
Oh, and also, if your gender dysphoria is destroying your mental health then focusing on fertility is just patriarchy. At the individual level, reproduction is a morally neutral act. Improving your mental health is a morally good act, so it clearly takes priority.