There Aren’t Any Updates Available
This is an annoying issue that a lot of people have found. With software issues, the best course of action is to update your iPhone ASAP. However, some people have reported that they can’t find a software update in the Settings app, even if they know there is one.
If you’re 100% sure that your iPhone supports iOS 17, then be sure to force close the app by opening the App Switcher and swiping the app up. If you have an iPhone with Face ID, you can open the App Switcher by swiping from the bottom to the middle of your screen.
If you have an iPhone with Touch ID, be sure to double-press the Home button to open the App Switcher.
Then, open Settings > General > Software Update and see if that fixed the issue. If not, go to Beta Updates (if you’re part of an Apple beta program) and turn off this feature.
If you still can’t see an iOS update 17, try restarting your iPhone and see if that does the trick.