You are correct that with a lot of the colors that are feather sexable, the males have lighter chests than their female counterparts. Not necessarily white, but definitely lighter. For instance, my male pansy fee's chest is noticeably more faded than the female's:
Male:
View attachment 2808077
Female:
View attachment 2808076
Also, a lot of males of feather-sexable colors have tan or a reddish color on their face. Example (not from this batch of quail):
View attachment 2808086
However, not all colors are feather sexable, and the ones that are not include most tuxedos (the combination white and colored ones). So although the tuxedos all have white chests, it is not an indicator of their sex.