Lots of good ideas at both of these places!
Heres a link for some free plans :
https://www.pinterest.com/pin/276408495861367527/
Also check out the group pg:
https://www.backyardchickens.com/articles/category/chicken-coops.12/
one of the members posted this... easy enough to build and it seems like these playhouses are always in the paper for sale. (or already in your backyard)
https://www.backyardchickens.com/articles/cottage-playhouse-plastic-chicken-coop.69399/
not a chicken expert by any means but this is the one that I've been checking into as my "grow up pen" for guinea keets it seems to have more room than most and you could always expand the run area...