Well there is going to be a county sized map so maybe that is what you are looking for? As for specifically pinning together small detailed maps to make a big one I would say it is going to depend on the cartographer. The scale of the map (and the level of detail) will be dependent on how the cartographer makes it. While there are some general guidelines on rough map scales and classifications, the majority of what makes each map special is who made it and what they choose to include/ what they know about. A good map maker whose maps will probably be in demand will try to make very high detail maps of large areas but that also takes more effort and skill. As such you will find a wide variety of both scale and detail in maps with an equally wide range in accuracy.

Sorry if that was a ramble but I hope it helps.

You will likely find that good cartographers may break up a major map into minor maps. A single kingdom may end up like a set of road maps IRL where you have various scaled maps and detailed maps in a large packet. Nothing is stated that says a map has to be a single sheet...

that would be like a book of maps, could be useful