That looks like enough space for 15 chicks at that age. A thing I see is there is little use of the vertical space, and there is no where to get away or out of sight. Adding clutter would help. Roosts, platforms, shelters such as totes on their side would really help… temporarily .
To get a healthy successful flock you will need to do some culling. This will help your full grown flock fit happily in the coop and run you have.
Birds being raised together have little to no influence on behavior. What does affect flock behavior is space, how the space is set up, and the gender of your birds.
I would suggest culling the roosters, they are becoming sexually active and competitive. That many rooster are just beginning to make the pullets lives miserable, this behavior will spread to other pullets soon.
If this is your first year with chicken let all the roosters go. IMO raising roosters take experience. They can be dangerous to other birds and to people, especially children.
Mrs K