Can you tell me how much the Amagi Brilliant Park anime adapted from the light novels, particularly in terms of which volumes?
The anime tells roughly the story of the first volume by expanding the deadline from two weeks to three months and by borrowing events from later novels. All of volume 2 was animated (hiring new staff and exploring Rubrum's cave), and the Kanie-body-suit incident was borrowed from volume 3.
NanoDesu Translations was DCMA'd and thus unfortunately was unable to translate the entirety of volume 3, so I'm afraid I don't have any more detailed novel-to-anime comparisons other than the fact that volume 3 did contain some story that the anime did not.
If we refer to bakaupdates, the anime covers the first volume but differs after that by taking elements of various volumes. https://www.mangaupdates.com/series.html?id=119404