Measurements give a clearer picture of the coop, or better yet a picture.
If you have a coop and an attached run, let everyone out to free range, and lock the new bird in the run. This will let her explore, find the hideouts, find the feed stations without being chased for her life. Do this two or three days. Then add 1 middle of the pecking order chicken to her.
There will be a bit of bluster, but one on one, it should settle fairly quickly. Keep this pair together 3-4 days. Next add a pair to this pair. Again, a bit of bluster, but should settle really fast at this time. Wait a day or two, then let them all free range together, and she should come back with the others and roost with the flock.
Mrs K