I have 3 coops. My main layer coop houses about 20 hens and is 7x8, with a run of about 25,000 sq ft... The only time they spend in the coop is sleeping and laying.
The second coop is an old camper, I think it's about 6x8, it has 17 juvies and a mom. Their run is about 100 sq ft. They spend time in there playing, and my free rangers lay in there, so its a come and go playhouse
My 3 rd coop is a silkie/broody coop. It's an old trailer tack topper... Yes I repurposed EVERYTHING.

its about 5x4 but its shaped like a triangle, and they have no run yet, free range is the common goal. That one has 3 silkies and 2 broodies getting ready for chicks.
I CAN say what a LACK of proper coop space will do....
Birds that roost in trees (the Anconas and Buttercups) because they got picked on so much in the original coop that they gave up and sleep in the trees. I let them, they like it lol...
Pecking order issues and blood drawn fighting for space.
Egg layers hiding eggs under trees, campers, woodpiles, and mulch piles because they don't like not having privacy to lay.
Poop build up from too many poopers in a small space.
Fights over the feed. And water. And treats. And that great spot next to the window for the roost.
It's like a sorority house sometimes
10x20 run... Coop should be at least 45 sq ft, IMO... I would actually go a bit bigger and increase it to 4-5 sq ft a bird, to 60-75 sq ft. Better to go too big and have extra room, for say, surprise broodies etc
Edit to add* I agree, being able to move the coops is a huge plus. We built the original coop on skids so it can be picked up and moved with the Bobcat. Camper can be hitched and moved, and the topper is also on skids to be able to move it. Never know when you may need to move the henhouse, so its nice to not have to completely deconstruct if it floods, etc...