Any chicken can become aggressive.
Small children's exuberant movements and high pitched loud voices can make chickens nervous/stressed and more likely to bite or scratch if pursued/touched by said children.

If you read enough stories on here you will see that any Silkie, Orpington, Rhode Island Red, Sussex, or any other breed can be a cuddly supersweet pet. You will also find stories where those breeds and all others are either super-aggressive toward the rest of the flock or are human aggressive. I'm sorry but you cannot go by breed on this.
I have another concern too, nothing to do with them being aggressive. This does not happen often but you can find stories about this on this forum also. Chickens investigate things by pecking them. Adults or children's eyes may get pecked. That's not because the chicken in aggressive or anything like that, just curious. They may peck other body parts and even draw blood but the eyes are my main concern. You occasionally read about dogs attacking young kids too. Not often, but it happens.
Personally I'd be careful about supervising young kids with chickens. As chicks I'd be worried about the kids hurting them by squeezing. When the chicks are older, I'd be careful about the pecking.