Yes White Leghorns are on a silver base as are blacks and blues I think. However, White Leghorns have dominant white as well as silver. Dominant white tends to mask most other colours.
Brown Leghorns are on a gold base but they often have autosomal red too.
So if you mate a Brown Leghorn male to a White Leghorns female, male progeny will be silver based whites and female chicks gold based whites. If that's all that is segregating in that cross, then there's probably a subtle difference on hatching.
However if have Brown Leghorn has autosomal red too, then most of the progeny will show some effect of that, so you won't be able to tell the colour of the genders apart on hatching.