How do I tell my 60 year old friend with mental disorder that she can’t wear booty shorts and bras outside.

I’m a live in caregiver for my friend who is 60 she has a intellectual disability that makes it hard for her to pay bills for her self cook and clean and do errands on her own. She is still very high functioning but I don’t think she really mentally understands what her body looks like at her age and how inappropriate it is for her to come outside in booth shorts and a bra. I think she has delusions and sometimes it comes off as being rude and cocky but I chalk it up to her disorder. She doesn’t even remember to take a shower unless I tell her too, but she wants to argue with me about her clothing choice. I was told I’m the first person to give her decent amount of allowance and lets her pick out her own clothes. I want to give her hefreedom and let her pick out her own clothes but everytime I do she goes and gets booty shorts and clothes out the junior section. I’m not a professional I took her in last year because non of her family members could at the time. If you ask her everyone who was a caregiver before me was too strict and controlling but it’s really her lack of self awareness and cocky attitude. For example she told me a story of how her sister would humiliate her about not taking baths or having good hygiene, but when I try to help her with her hygiene or appearance It’s often a struggle. It’s always someone else’s fault and never hers. I try to get her to understand that she has to be well taken care of and presentable because the state can check in anytime. I just wanted to know if there’s anyone out there who ever dealt with this from there special needs friend or family. Thank you sorry if it’s tmi