One of the first movies I seem to remember that scared me was “West World” I was probably 4 or 5 at the time. I rented it from Netflix not long ago. It was good therapy. LOL.
I think the scariest horror movie I’ve watched is Pet Semetary. I was 19 and I remember feeling nauseous and breaking out into a cold sweat. It wasn’t so much what was shown in the movie as what was implied.
Have you read the book. It is even scarier than the movie.
Westworld frightened me, too. Yul Brynner was terrifying.