I don't see any barred Rocks
But yeah, at this age you're looking at the combs mostly. Cockerels will be leggier, and the reddish coloring on the wings (or any brightly colored bird that makes you say Wow, it's so pretty ) is a male thing.
Where did the birds come from? Are they from a hatchery or a breeder? What were they sold as?
I see a couple cockerels, the bright red birds (I think there are two?) with red combs are male.
In this picture, the birds to the far left and right are male, the others look female. And...