I only have 2 hens, and they are a bit smaller than my Welsummer hen who is about as heavy as a cinder block. Most of their "size" comes from height. They are quite leggy. I have heard that the size difference between Breda hens and roosters is pretty significant, though I've never owned a male so I can't say for sure.
I would think that usual coop size requirements for the usual chicken would work fine for Bredas.
![gig.gif](https://www.backyardchickens.com/styles/byc-smilies/gig.gif)