Barred Rocks are usually easier. The others you'll have to wait a bit. I look at extra thick legs to id cockerels in RIRs and others.
Barred Rock Sexing takes three traits together to determine sex:
Male: lighter gray/silvery frosty color, large splotchy headspot, and legs with little to no dark wash down the fronts
Female: very dark, black down, smaller and/or more defined edges on the headspot, and some black wash down the leg fronts.
Some defy the rules, but you can almost always sex BRs this way.