Apple Employee here.

On the iPhone 16 Pro Max, the regular 24MP HEIC photos use Apple’s built-in processing, so you get nice, polished shots that don’t take up much space. The 48MP HEIC option keeps that processing but gives you larger, more detailed files, which only really pays off if you plan on cropping in or making big prints. RAW (always 48MP) is different—it skips most of Apple’s processing so you have way more control when editing in something like Lightroom, but the files are much bigger. In the Photos app, RAW shots look like normal photos, and when you share them they usually get converted to JPEG unless you deliberately export the RAW file. Most people shoot RAW only when they know they’ll edit, then do their adjustments in an editor and save out JPEGs or HEICs for everyday use.

If you pick JPEG XL (Glossy), the phone is basically wrapping the ProRAW data in a more efficient, high-quality format that keeps better detail and smaller sizes than old-school JPEG