You can try pin less peepers. They are little 'glasses' that have worked well for a lot of people with smaller flocks. It interferes with direct sight, but not with eating or getting on the roost. So they quit bullying the smaller birds.
Some people can get a flock of standards and bantams to work, but a lot of people have the same issues you are having once everyone gets full size.
Another issue that can help is clutter in the run, little mini walls, roosts, boxes laid on their side, pallets leaned against a wall, something where a bird can get out of sight, out of mind of a more dominant bird. I have seen a Queen, give a peck, the lower bird vanishes, and a minute later back out eating next to her. She bowed to the queen, and it is over.
Where as, a lot of runs, are just a wide open rectangle, where as a bird can see every other bird 100% of the time. So the Queen pecks, the bird has no where to go, so she pecks AGAIN and harder, and still no place to go, and it gets ugly.
Multiple food bowls, set up so that a bird eating at one station, cannot see a bird eating at another. And a group of bullies cannot keep others from eating.
Mrs K