Okay soo... I can go a lot of ways with this.. if you want truly cozy, i.e lighter, comedic.. maybe I am not your best recommender, haha.
Or pls define cozy and I can try my best.
Here's some I enjoyed. Darker, perhaps or maybe typical, but here ya go regardless:
The Silent Patient- Alex Michaelides .. maybe a more well known suggestion.. if you were cool with Gone Girl, etc. still good.
Night Film: A Novel - Marisha Pessl .. dark creepy thriller. Good if you are a fan of horror films/general weirdness.
Dept. Q series - Jussi Adler-Olsen ... Nordic(ish) mystery . Cold cases. Some darker than others. Also have been made into films.
7 1/2 Deaths of Evelyn Hardcastle - Stuart Turton...more Agatha Christie vibe. Like an escape room, in book form.
I've got more, haha. Lmk.