Up to 8x10 as noted, larger would be a custom back, which isn't that hard. You can see examples here, and learn about the Norma system. Glenn's high though.
The reason LF folk tend to "get big" is because a lot of people contact print using both normal and alternative processes, so you need a camera the size of the finished print. A lot of people don't stop to think that there was a time before enlargers - actually quite a lot of time - when you used a camera that was the size of the desired print.