I'm a 61 year old woman. Of course any woman can wear whatever she wants but it won't stop other people thinking that some outfits or styles look better on young women and silly on older ones.
I see lots of young women walking around with very tight fitting short crop tops and shorts with their buttocks hanging out. I think they look pretty silly with part of their bum showing but as they're young they can get away with it, but if someone my age wore such an outfit to my local shop I would be very surprised and I'm sure the phrase" mutton dressed as lamb" would go through my head, as well as thinking she was an attention-seeker and probably had self -esteem issues.
I occasionally go to bingo and a few months ago saw a woman who must have been in her late 70s wearing a very tight, short dress totally covered in silver sequins. She looked absolutely awful and her face and hair were very incongruous with such an outfit, no make up and a nondescript short haircut. She got a lot of looks as she walked down, obviously because bingo isn't a place where people dress like that anyway, but she was wearing a dress totally inappropriate for her age. Presumably she felt great in it and in the end that's the most important thing, but I wonder what the people she was with thought.
I have a neighbour who is my age and wears great clothes but dyes her hair pillar box red with a blonde stripe. Looks bloody awful at her age. Again presumably she loves it but it makes you look twice, and not in a good way.
You can look cool and stylish at any age, my 88 year old mother loves clothes and looks great, but she wouldn't wear some of the clothes that her 25 year old granddaughter wears. There is such a thing as age appropriate clothing which is what the phrase" mutton dressed as lamb" means.