iPhone 15 Plus camera is not working

if it was me then I would

try restarting the ios device Force restart iPhone - Apple Support and check if it resolved it

if it did not then I would try Restore your iPhone, iPad, or iPod to factory settings - Apple Support -

if that did not resolve it then I would contact apple about repair Contact - Official Apple Support

Test the camera by trying to take a photo. Test the LED flash: Try the torch in Control Centre on your iPhone or Control Centre on your iPad. ...

If the camera or flash on your iPhone, iPad or iPod touch ...