Yes, definitely increase protein for breeding. Hens need it for egg production, cocks for fertility.
I switch from racing mix (14-15% protein) to breeding mix (17-18% protein) about 2 weeks before pairing. The extra protein comes from more peas and legumes.
Also add more safflower for fat/energy. Breeding is demanding on the birds.
I don’t feed cocks and hens separately - too much hassle. Same mix for everyone during breeding.
In Germany we have a saying: “You can’t breed from a empty bag.”
Breeding birds need to be in excellent condition. Not fat, but well-muscled with good reserves. I actually start conditioning my breeders 6 weeks before pairing.
Protein up, exercise down. You want them focused on breeding, not flying.