this is a 4-book series that is a sequel to her The Seven Realms series (also 4 books)that i read several years ago. both series are YA fantasy.
i was reluctant to start these books because i was afraid i would not like them as much as the other books. i did like them, with some exceptions that i will get into in the spoiler section.

this series is set 25-30 years (there's a time jump) after the first books. there has been another war going on because a prince (now king) of another realm was mad that the woman who became queen in the last series had rejected him for marriage. he's had his brother killed to become king and has subjugated the other realms & he can't conqueror the queendom because it is 90% mountains and his army is really only good on flat land.

in the first series you could possibly handwave their ages and consider the main characters to be 20-22, but you can't do that in this series because they mention ages a lot. and it's Young Adult (which i rarely read), so all of the main, and most of the secondary, characters are teens.

( all kinds of spoilers )

there's more LGBT+ representation in these books in the first series (if that's what you're looking for in YA fantasy). in that one 2 very minor female characters are in a relationship. they get a brief mention in one of the these books, but in this series there are two young men that briefly spent time together & spend about 95% of the later books separated and yearning for each other.
there might be a transgender character too. the wizards/mages are referred to with he/him (it was the same in the first series too) but one is she/her. i probably should not speculate, if it's not what the author intended. but they are the only wizard/mage that i can recall being referred to with she/her.