The Blair Witch Project was goddamned terrifying in theatres - they successfully convinced moviegoers prior to the premiere that these kids were actually missing, and they were releasing the last known footage of their lives. I don't think anyone could get away with that again.
Antichrist. Watch a relationship fall apart and give manifest to some pretty nasty stuff.
You must see the Wes Craven's filmography, I love him. And there outside are very good foreign terror movies like The Wailing, Saint Maud, Shutter, etc. Hereditary is one of my favorites too.
The Autopsy of Jane Doe No found footage nonsense- its all shot like a normal movie. It follows 2 coroners performing an autopsy for the town sheriff. The dead woman appears to be in perfect condition on the outside but not on the inside. What starts as a mystery builds into a horror thrill ride by the end