What does your run look like? Is it a wide open space? Where a chicken can see every other chicken 100% of the time? If so, you need to add clutter. Platforms, roosts, mini walls, wind shelters, hideouts. A platform low to the ground that a smaller bird can escape to can help. Or a pallet wall pen, where a smaller bird can slip between, but a larger one cannot follow will really help. Set up multiple feed stations, but set them up so that if a bird is eating at one, she can't see a bird eating at the other. For chickens, being out of sight is out of mind.
Another trick, is to lock the big girls outside the run and coop, and let the chicks be inside the run/coop. This lets them explore with out being chased. To get comfortable at the feed station. Let the old birds in at as near to dark as you dare... the urge to roost will nearly be the same as the urge to fight. Check on them early in the morning.
MRs k