They came from a small farm incubator hatch. May not be pure BR. Barred Rocks at this age seem hard to sex because a lot of contradictory info online. Also this breed male and female adults have combs.
I do think one may be Dominique for sure. The farmer had a mixed bag of Chickens but was told they were BR. I live in city limits so I can't keep roosters. I have 6 Rhode Island Reds and 2 other adult BR hens.
If the farmer had a mixed bag of chickens then they are mixed breeds, unless he had breeding pens set up. They all look like cockerels to me, possibly black sex link cockerels.
Pure barred Rocks at this age aren't usually too hard to sex. The confusion comes when the birds are mixed, then the "rules" of sexing don't apply. But, no matter the breed, that much comb and wattles with that much red at this age indicates male.
Dominiques have a rose comb. I'm not sure what kind of comb that last bird has, but it doesn't look like a rose. Possibly a mixed comb?