If you plan on taking all your pictures in 48mp RAW, I'd go for 512gb at least, but I personally only switch to RAW if I plan on editing each photo individually later or in challenging situations (backlit, high contrast, etc). I wouldn't bother using it for casual snaps or events where you take hundreds of pictures.
I wish there was a way to convert a RAW picture to HEIC ou JPEG using the native photos app, though. IMO it does a better job in handling the DNGs than Lightroom, and is also able to keep the HDR profile.