So that's a good amount of space for 3 but you mentioned the landlord destroyed some platforms... so what's currently in the run space? Since you have a bullying issue, is there clutter: https://www.backyardchickens.com/threads/a-cluttered-run.1323792/page-6#post-25037140 to break up the space and maybe an extra feeder or waterer placed apart from the first to make it hard to guard food?Oh, so maybe time will tell but I did notice the bully leghorn's comb has lost color - may indicate sickness. They're all 3 in a 3x4 meter cage with bird netting as the cover so they have good exposure to sunlight (they love chilling in the sun) they've got two henhouses one on each corner but since the breakup I've devided it. They've never really used the second henhous they all just go into the bigger one. They had raised platforms but literally since yesterday the landlord destroyed it so it's gone. Overall they're very happy, the amber star runs to me when I great them and when I'm not feeding them she wants to jump on me to get a ride, she's very good. The big leghorn is behaving like an antisocial menace and the small leghorn is behaving like an insecure victim but she's getting better. The two leghorns tend to follow what and where the amber star is doing
Other significance in asking where you sourced the 3 birds from is if they were all brand new to each other (never met) that could definitely worsen any pecking order issues, as chickens have a social structure and naturally want to chase away unfamiliar birds.