You need some stuff to break up the line of sight. You (chickens) can see all around the run by standing in one spot. Need to make that not possible. The littles will be able to hide and run away better if they can run around things or under things that break up the line of sight. But no dead ends. So like an ally. A couple pallets leaned up against the walls of the run with old feedbags zip tied across the flat surface so they can't see through the pallet. Or old garden gates or something, with old feedbags zip tied to block the line of sight through the gate. Old boards/plywood, leaned against the walls, so it's like a tunnel, with free access on both ends.
ETA: this will help the littles "hide" and not offend the bigger ones with their presence
Also add another feeder and waterer station (I only see one set in the run). That way the big chickens can't prevent the littles from getting fed/watered, and if you can break the line of sight between the two sets of feeders/waterers, and put them on basically opposite ends of the run, that would be perfect.