Don't really have any advice, but just want to offer some solidarity. My DS (biologically male) was "gender non-comforming" from as early as he could express any preferences. I allowed him to just wear and play with what he wanted (two older siblings with a variety of hand me downs helped with this). Didn't really think too much about it.
However DS (now nearly 14) has very much persisted, and from age 11ish asked his friends to use female pronouns. At this point the school kind of got involved, as DS was asking them to use female pronouns. We had several meetings about this, and we ended up giving permission, as DS's relationship with us was getting increasingly strained (he knew we were the "bad guys" standing in the way of socially transitioning at school). We now use female pronouns at home.
Honestly, I don't know if we did the right thing, but it ended up feeling like we had no choice, as DS was so distressed/angry when we used male pronouns. And before anyone jumps on me, we are NOT pushovers as parents, and it was only after a couple of years of trying our best to hold our line that we decided it was having a detrimental effect on our relationship with DS.
Before having DS (DD!) I thought that "trans kids" were the product of homophobic parents, and/or traumatised, but that's not the case with us. DD does have severe ADHD, and I know there's a connection with gender dysphoria and neurodiversity.
Anyway, just wanted to add my voice to the mix, as there are a lot of posters who are telling you what you should/shouldn't do. I very much understand their opinion, and a decade or so ago, I'd have been right there with them! I'm not saying they're wrong, just that sometimes you need to be pragmatic when it comes to supporting your DC.
I don't think make-up or wigs are necessary at that age though! 😊