Hello 
and Welcome to BYC! There are a couple of huge Orpington threads in the Breeds, Genetics & Showing forum, like this one. https://www.backyardchickens.com/t/259995/post-pics-of-orps-orpingtons-here/12070 you might be able to get some breed-specific advice over there. With coops, if you can go bigger, it is always helpful to have extra storage space, and of course allow for more chickens if you decide you want them later.
and Welcome to BYC! There are a couple of huge Orpington threads in the Breeds, Genetics & Showing forum, like this one. https://www.backyardchickens.com/t/259995/post-pics-of-orps-orpingtons-here/12070 you might be able to get some breed-specific advice over there. With coops, if you can go bigger, it is always helpful to have extra storage space, and of course allow for more chickens if you decide you want them later.
