iPhone camera not working after updating to iOS 18.3

First, try a forced restart. If that doesn't work take it in to the Apple store to have it looked at.

• Press and quickly release the volume up button

• Press and quickly release the volume down button

• Press and hold the side button.

• When the Apple logo appears, release the button.

Force restart iPhone - Apple Support (IN) Force restart iPhone - Apple Support (IN)

Make an appointment at the Genius Bar to have it diagnosed.

Genius Bar Reservation and Apple Support Options - Apple Genius Bar Reservation and Apple Support Options - Apple

Try iOS 18.3.2.