OP, your daughter sounds like a tyrant.
So fed up of her own filthy room is she that she prefers to move into your lovely room, sit at your dressing table and mess up all your stuff like she has her own.
You should be very angry about that. It’s disgusting behaviour on her part.
The question is …why do you allow this to happen?
The longer you leave the show-down where you lose your acceptance of her filthy, lazy, selfish, slovenly ways and tell her exactly what’s what, the worse she becomes and the more she takes advantage of you.
It’s your job to tackle this head on if you want her to be prepared for life.
She needs a short sharp shock at how lucky she is not to be paying board and lodging. You need to get very tough.
Tell her that she has been taking advantage of your good will long enough and you no longer like the person she has become so you now have to issue an ultimatum.
Tell her you have thought about it hard and you will no longer
enable her to live like a filthy pig in your home.
Either she behaves like an adult or she is no longer welcome to take her room for granted.
Tell her that if she can’t sort her room to your own level of cleanliness and tidiness by Sunday afternoon then the room is no longer freely available to her after leaving it on Monday morning. When she asks what that means, tell her you will be in that room on Monday morning and every Monday morning from now on, to check it’s clean and tidy to your expectations.
Make your expectations and rules very clear. Tell her if your expectations aren’t met, you will be binning everything to the garage, cleaning everything in there and using the room for other purposes and so she will no longer be able to consider it her own, but will have to ask every Sunday evening if there is a room for her for the next week.
Make it crystal clear that taking her privileges for granted and abusing your wishes have led to this and if she doesn’t step up and start acting like an adult, grateful for her free board and lodging, you will take your own measures to sort it.
Tell her you are available to help her sort her room for an hour or two on Saturday morning at 9am. But after that she has to maintain it to your standards on a weekly basis until you can trust her again.
And tell her to buy her own hair dryer and straighteners as your room, make up, jewellery is no longer available to her ever again. Your room is your own private space and sadly, she isn’t welcome in there to mess with your stuff.