If you liked: Annihilation by Jeff Vandermeer you might like: Our Wives Under the Sea by Julia Armfield this comparison is going off vibes more so than story, but bare with me here. Both novels gave me the same feeling of subverbal psychological dread, that comes as much from the liminal/alien feeling enviroment as from within. They capture a feeling of paranoia and distrust for an enviroment that should feel safe, but now seems foreign.
If you liked: Mexican Gothic by Silvia Moreno Garcia you might like: The Ghostwoods by C.J. Cooke building off the previous recommendation: if you liked the dilapidated, moldy-stained manorhalls of the House of Usher as a setting, both these novels borrow the atmosphere and put a whole new spin on "fungal horror"...
If you liked: Here there are Monsters by Amelinda Bérube you might like: The Twisted Ones by T. Kingfisher This one only works one way for me personally, as I didn't love the former. If, like me, you liked the creepy forest setting and the idea behind these creatures, but didn't like the juvenile protagonists and teen drama: The Twisted Ones is for you. It also happens to be funny as an added bonus as well.
If you liked: Ghostlight by Kenneth Oppel you might like: The Curse on Spectacle Key Brave young protagonists undertake a ghostly adventure investigating haunted lighthouses.
If you liked: Goosebumps by R.L. Stine you might like: Small Spaces by Katherine Arden what Goosebumps did for 80's and 90's kids, Katerine Arden is doing for kids of today. These series of books take a middle-grade spin on classic horror-tropes, destined to become classics themselves in the process.