According to Ming-Chi Kuo a 48-megapixel sensor main camera with a f/1.6 image sensor will be built into the iPhone 15, which is a faster (wider aperture) than the Sony IMX-803 which is in the iPhone 14 Pro and is expected to be retained in the iPhone 15 Pro.
(Don't expect Apple to allow access to the ProRaw feature on the non-Pro phones, however, so pixel-binning to 12MP and better digital zoom is all this will be used for.)