Fallout 76 is going to have a reasonably-sized map, if by 'reasonably-sized' we mean no less than four times the size of Fallout 4's map, according to Bethesda. Now, it is a given that this is a tiny bit of an overstatement, because the usable size is probably smaller, but still.
Just below this paragraph, you'll find a rather lovely rendition of Fallout 76's West Virginia, and though there's no Pip-Boy icons and names to be found on it, you can definitely get a solid sense of what's what depending on map colours and various markings. Here's the Fallout 76 Full Map.
Now, while Fallout 76 won't be particularly interesting to modders upon launch, if Bethesda are capable of bagging this sizeable location full of interesting locations, enemies, and loot, that ought to keep most of the people quite content with what they've got in vanilla.
If you've got the chance, you could give the map a go in Fallout 76's official beta testing schedule, of course, but there's no telling if and how much the beta is gimped in regard to content, compared to full release.
As it currently stands, Fallout 76 is going to be coming out late this year, on 14th of November, so it might be the time to start cranking that hype train at this point, really.