I agree with Elderoo - more and more and more outside space per bird is best. Inside coop they just go to sleep so not really an issue unless you leave them locked in coop all the time. BUT...outside is a different story. Mine all freerange our farm - fence free. They have all the space they want. While there is a possible predator loss (a good guard dog helps) I don't have any issues with them pecking or picking on one another, no feather eating issues, no cannibalism, no egg bound issues - no fighting whatsoever and I mix new baby hatchlings and every age group together and they all get along - even with the ducklings and ducks. Even had someone drop off some chicks and put them in with the rest and still no problems. Also have a 4-month old chicken that hatched with a deformed leg and must hop to where she wants to go and then lay down, can't roost, and not only do they NOT pick on her, many of them can be seen laying next to her as if to keep her company. I've never seen anyone pick on her.
I truly believe it is all because they have so much space and no one has to be in another's personal space and they have so much to do with running around all day long they don't worry about fighting with each other.
I truly believe it is all because they have so much space and no one has to be in another's personal space and they have so much to do with running around all day long they don't worry about fighting with each other.