Yes yes yes to this. I love the Winternight Trilogy! The fairytale atmosphere is so magical.
If you’re not opposed to reading middle grade, the Nevermoor series is amazing. Reading it is like being wrapped up in a comfy blanket of nostalgia (even though I’d never read it before) while sipping hot chocolate with some fluffy marshmallows on the side. I was gifted the first book by someone who didn’t know me very well or the reading world in general, thought “ugh, middle grade”, then read it and loved it. That said, it’s not really a dark series.
The Cassidy Blake series by V. E. Schwab is also middle grade, but it was such a fun book. The first book is City of Ghosts, and this one is darker.
I don’t read that much ya fantasy, but I can recommend Laini Taylor’s Strange the Dreamer duology. The first book is quite heavy on the romance, but I didn’t even care that much, and I usually get annoyed whenever a romantic subplot takes over the story. The second book, however, is just amazing and it definitely gets darker.