Chickens only use the coop to lay their eggs and go to roost at night. Their ranging/foraging area is what needs to be roomy. We keep the feed/waterer outside the coop and don't leave the feeder out overnight. The main thing is that the chickens are secure, secure, secure from predators whether roosting at night or foraging in the day.
The coop is secure now. That picture was taken while we were in the process of building. We won't be doing a run or pen for them because the coop is in the middle of the horse pasture that is fenced with high gage steal wire mesh that's sunk into the ground 18". Plus we have a mule who's been known to kill coyotes and chase off mountain lions, and 2 LGD's who have gotten their fair share of Fox and raccoons, so no predators are dumb enough to come into the pasture anymore, not even snakes because they avoid being anywhere near the horses. We also have little shelters set up for cover and a good roo who looks out for hawks. we made sure nothing can get in or out of the coop at night before putting the girls in there. Only one we need to worry about at night is the roo because he won't sleep in a coop he likes to roost 30ft in the trees at night, but nothing has gotten the old guy yet so I'm sure he's pretty good at taking care of himself. Plus he's safer outside with the owls than he is inside with our dominant hen lol