The second season of Outlander is set in France, and it has been a significant decor upgrade. In season one, we were lucky when a room didn't have a dirt floor. Now every set is lavish beyond compare.
If you study this alternate angle, and pay closer attention to the books, they look like they are wallpaper. See how everything is so perfectly flush. I had assumed this was a real library, but now I think it is a built set. And if that's the case, I am deeply impressed.
In a later episode we follow Claire from the first library, into a second one. This one feels "real" because the books are more haphazard on the shelf, and show more depth.