Set some limits - eg no make up, and allow him some dressy up stuff.
Broaden his horizons around gender stereotyping; look at male footballers who wear pink and female footballers doing really well (v easy at the moment!)
Then broaden his horizons generally away from all this self absorbed aesthetic stuff, some outdoor activities and sports. Riding, gymnastics, parkour if he won't do usual team stuff. I think kids are getting too into media and self image generally these days and being physically active is really good for them.
Sport also highlights the need for physical health and fitness and that there are real differences between the sexes, the rest is just consumer led decoration.
He's not trans and you know this but you just need some help to help him to navigate this very consumer driven world kids exist in now.
A child I taught who was seen at the Tavistock years ago (before it was swamped by lobbyists) was similar and was told that he was "very into fashion." They suggested to him he might be gay but I wouldn't bother with anything like that at this age.
He took that on board and became very swish in his fashion sense as he went through his teens. The child had no issues with his body but it was starting to make him frustrated that there's were all those social rules he didn't understand.
He would have loved Harry styles.
(Take him to see Harry styles...!?❤️)
The Bayswater support group are excellent.
www.bayswatersupport.org.uk/