Yup. Eggy is probably right. I'd just insist on the fact that HEIC is a much better format than jpeg. Better quality, smaller filesize.... So switching it off completely to have your iPhone shoot directly to jpeg might not be what you are after... (but it could, of course...)
Also, note that HEIC isn't Apple's property. A lot of people seem to think so, but it's not the case... It's probably only a matter of time before Adobe finally (Common Adobe, this is getting ridiculous...) support it in PS.
Then, some of you might be interested by the fact that iPhones can actually capture "RAW" images. The default camera app doesn't (unless it changed recently ?) but many third party camera apps offer this feature. Honestly, this is a MUST for anyone serious about their iPhone photography... Image quality is immensely better, has it bypasses all software hacks Apple added over the time... You will not be able to use advanced features like "portrait-mode" or whatever it's called, but the fine details in your photos will be captured waaaaaayyyyy better.