I mean, combs and wattles on the males get a little bit bigger and redder than on the females. Then they get even bigger and even redder. As time goes on, the size and color differences become more and more obvious: males have them big and red, females do not.
There does come a point when the females are about ready to start laying, when their combs suddenly grow bigger and turn red (but not as big as the combs of the males.) But by that age, the males usually have long skinny saddle feathers hanging down on each side of their tail, and some big curving tail feathers, and could not possibly be mistaken for females.
There can be a few confusing ones that are not obvious, but after you've looked at enough hundreds of male and female chickens, the sex differences really do seem obvious on most chicks of certain ages. (Like how man vs. woman in humans is obvious for most people.)
I suggest that you start a thread in the "What Breed or Gender" section of the forums:
https://www.backyardchickens.com/forums/what-breed-or-gender-is-this.15/
Put in pictures of your chicks, with some way to identify which chick is which (names, numbers, or colors can all work well.)
Then people can give an opinion on which of your chicks are males or females, and may point out which details help them decide.
