Potentially slightly spicy take: full respect for bodily autonomy means respecting the right for people to, assuming they do so knowingly and while informed, consent to putting themselves in situations where they cannot easily, readily or even at all withdraw that consent once given - and this includes during sex.
I have sometimes seen ostensibly sex positive people opine that it is impossible to consent to chemsex even if consent is granted while sober, because not being sober in the moment means that you don't have the capacity to withdraw consent, and the ability to withdraw consent is required for sexual consent to be valid. There are many thinkpieces online, some by academics, expounding this opinion.
While this might make sense for the default case where nothing to the contrary has been specifically negotiated, it is completely incompatible with several understandings of consent and bodily autonomy we routinely apply in non-sexual contexts, where it is understood that of course someone can choose, if they so wish, to put themselves in a situation that they cannot immediately extricate themselves from.
If you choose to get on a roller coaster, you can't unbuckle yourself from the ride once it's in motion, even if you're really scared and want it to stop. Does this mean that you didn't really have the capacity to choose to get on the ride? Of course not. It's a risk you can choose to take.
If you're getting an elective surgery, consent cannot be withdrawn once the doctors put you under. Does that mean that all surgery is implicitly a violation? Of course not. People have the autonomy to put process that will affect their bodies into motion.
Most contracts cannot be reneged upon once signed. The agreement is legally binding. Does that mean that nobody can consent to sign such a contract? No, if you understand what you're agreeing to, you are empowered to make that choice, and the law and society recognize this.
If you decide to scale a rockface while mountaineering, you can't renege on that decision half way up the rock face. Does that mean that you can't consent to attempt the climb? That anyone who sells you gear is complicit in enabling your self-assault? No! This is obviously absurd.
Sex is not some alien domain with a separate, inscrutible rubric; like everything else in life, it's just an activity that people can choose to engage in, and that includes them having the autonomy to make the decision to undertake a certain amount of personal risk.
To take a more common example, BDSM implicitly understands this in a lot of contexts. You can consent to being tied up and gagged if this is pre-negotiated as a scene; once you are tied up and gagged, even if you have some signal, the ropes cannot be untied immediately. This is known and agreed to before the scene commences, because, again, bodily autonomy includes the right to put yourself in situations you can't immediately leave. And yet this baldfacedly contradicts a naive absolutist interpretation of "consent must always be revokable". There are, of course, some people who genuinely believe that such BDSM scenes can never truly be consented to; we call them radfems and swerfs and rightfully shun their wrong and harmful opinions in sex positive spaces as they deny bodily autonomy.
But some people do not take this idea to its conclusion, and carve out clumsy exceptions for activities they personally deem too extreme or risky. I'm here to tell you, respectfully, that it is none of your business, and that you cannot leave exceptions or carveouts in personal bodily autonomy, even if you think it's for the person's own good. (Every conservative opponent of bodily autonomy thinks that their strictures are for the person's own good! That is missing the point!).
So yes, that means that the somnophilia fetishist can consent to letting their partner feel them up while they're asleep. That means that the cnc fetishist can negotiate a scene where they are bound and gagged and not given a chance to say no. And yes, that means that somebody can agree while sober to have sex with their partner while they are drunk.
Bodily autonomy means respecting the right of people to make those decisions, and not vilifying their partners for taking them at their word when the negotiation was in good faith and where there is no reason to believe they didn't understand what they were agreeing to.
