First off, it's not a crest, it's a comb. And right now it's too early to tell. Second, behavior such as that does not have any indication of sex. Hens can be just as bold as roosters, depending on their stature in the pecking order. Wait and see, that's all you can do.
i believe reds are more agressive or rather strive to be dominant when given the chance, than other breeds at times. I think in this case, give it a few weeks. my red roos' comes turned red faster than all of the pullets, so you should know soon enough. also keep an eye on the tailfeathers, mine started getting to shiny greenish black ones pretty early too
mine was more interested in what was going on around him even as a chick when I just suspected. My EE's are far more dominate as adults. I am keeping a close watch on a beautiful red, white and grey rir x ee and yesterday I spied irridescent green tail feathers, Im still crossing my fingers that its not a he. The other 3 yunguns are just plain red. If its a he I dont think he will stay, I already have 1 rooster who needs more hens.