It disguises itself as many frightening things in the movie.
Pennywise can morph his mouth into a giant gaping mouth with layers of sharp teeth which he uses it mangle and eat his victims. This is all done with CGI.
The finale is intense and involves scary imagery and loud noises
Two children are killed by Pennywise on screen. They are very disturbing to watch, but not really all that graphic and you don't see much of the impact.
EPILEPSY WARNING: This film has several scenes that use severe strobe light effects. The most intense ones happen in a pharmacy basement, in a house of mirrors, and interwoven through about half of the climax of the movie, which lasts roughly half an hour.
The first scene is extremely disturbing.
In the beginning of the film, Beverly is seen floating with white eyes and looked like she was getting possessed by a ghost. This may scare young kids
Beverly is shown to have a sexually abusive relationship with her husband. He doesnt trust her when she says Mike is just a friend and hits her multiple times with a belt and she then hits him on the head with a blunt object. As she runs out the door, he screams "youre nothing without me!"
The opening scene is extremely upsetting. It isn't as scary as it is disturbing and depressing.
Many many jumpscares. They are usually very predictable though and not that scary, unlike in the first one.
There is a scene later on that is super claustrophobic and intense
There is a suicide scene early in the film that is very sudden and unexpected, and it's a sad and heavy scene. It's only shown for a few moments, but may be very upsetting for viewers sensitive to this topic.