The whole "adult" thing in this post drives me fucking insane. I don't even want to talk it out (okay, I did end up with a rant), just, if you think bodily autonomy only applies from a certain age, Fuck You. This is probably the most adultist post of that kind I've seen, usually they just mention "if they are old enough" and "[x category] are not children" like once each but this one literally makes the Entire Point that deserving autonomy is an adult thing.
The "legally adult" part also makes this so fucking laughable. Your right to autonomy is determined by your local laws! That is why there shouldn't be other local laws restricting your autonomy. Jesus fucking christ??
And fun how apparently according to the op at, for example, 12 y/o, you are not old enough to decide you never want to carry children, but are old enough to carry children, then, I guess!
Or not old enough to decide they don't want breasts, but old enough to live with unwanted breasts. Ee tee cee.
And less on the general topic but lol no, actually, if someone decides to join the army they are not making a choice about their autonomy only, they are also deciding, you know, to join the army. Which in many cases just means joining in on imperialism in an active part!