So another parent said something similar to me about washing. That her kid refused to wash themselves and said "it's my body so I get to choose" and that they weren't sure what to do without demeaning that sentiment.
If it's helpful, from really early on we said to our kiddo "As your parents, it's our job to keep you safe and healthy. We will intervene if it has to do with your safety or your health." and after that it's really easy to be like "this is a health/safety concern so do you want me to intervene or can you do it yourself?" Just don't use it for evil LOL be honest with yourself about whether or not it is because they WILL get old enough to know the difference and if you're full of shit and then it's over