My coop is almost 210 ft sq, and this size will depend on your climate I guess, do you have a harsh winter in your area usually? If you can't let them out during winter then its better to give them more space in their coop, i'm just throwing ideas, we never had harsh winter here.
Maybe you...
They said every adult peafowl needs 100 ft sq of space, and if you can make it bigger it will be better, here are many pictures for peafowls pens designs i collected from google mostly or from this forum: