Depending on breed combs and wattles can help. But I've read that when it comes to the wyandottes some develop early on and is not a true indicator to sex. Im currently in that situation right now with 4 wyandottes(2 silver laced and 2 gold laced) 2 of the 4 already have red combs and wattles and the other 2 don't. I've read on another thread to wait it out that that is many times a false indicator for the breed.
I'd say dive deeper into it breed specific as you didn't tell us the breed of the bird in question