I have 2 male cats ~ Ragdoll Xs so quite large. Both give all the chickens a wide berth. My hunter was disciplined by a BR pullet early on. She stretched her neck up & her wings out & I've never seen a hunting cat back down so fast! The other cat is a sweetie but unfortunately for him I have 3 Vorwerks who will actively hunt the cats. I found Cat & my largest & most aggressive Vorwek having it out on the back patio. The Vorwerk was the aggressor & kept moving in pecking & beating @ the cat, who attempted to bat her away so he could slink to the door to be let in. She was having none of it. The cat was cowering in between swipes but allowed to continue I expect he would have attacked the hen in sheer self defence. MyJaps are tiny but neither cat has ever attempted to harrass them. Once a cat has learned that chickens can be aggressive they give them a very, very wide berth.There are 3 cats at my place (they are not my cats personally) plus some from the neighbors. They are all absolutely and completely terrified of broody hens. I've watched each of the cats being whomped by the hens. They only take a beating once and then stay well away. I was worried by my sister-in-law's cat as this one actually can catch mice and birds, but she is fully terrified of the hens too when they have chicks.
If you have a tough broody mama I wouldn't think cats are going to be your problem.