Yeah I support kids being able to play with gender and experiment. However I know from my experience that as a kid, I was a tomboy. I had short hair, wore boys’ clothes and identified strongly with “George” from the Famous Five series. I fantasised about being male characters from my favourite stories — Han Solo, Derek Wildstar from Space Battleship Yamato, and The Phantom. If I’d been told by my parents that I therefore must actually BE a boy trapped in a girl’s body, I might well have believed myself to be transgender.
I’m not though. As time went on I experimented with both more masculine and more feminine presentations, and I now feel very comfortable dressing in a style that’s like “nature goddess” — bright flowing dresses, rainbow colours, flower crowns etc. I wasn’t pressured into it, and sometimes I still enjoy cosplaying as male characters (such as Castiel from Supernatural or Frodo from Lord of the Rings) but I’m very very comfortable in myself being a woman.
Kids should be allowed to dress how they want, explore their identity however they want. This should be encouraged. However parents should be wary of trying to put labels on their experimental kid, that if they dress up in a non conforming way, or act in a non stereotypical way from their assigned gender they must “therefore be trans”. They might be but they’re probably not.
From my experience (which I know isn’t everyone’s experience), I don’t actually have an innate sense of “gender identity” that’s separate from the lived experience of “being me, with my body”. So I’m glad I got the chance to experiment with what “being me” meant to me. And for all kids that will mean different things at different times.