Hello,
There are different ways to ensure the highest iOS that your device will support is installed on your device.
Any equipment currently running iOS 12.5.7 can't be updated to anything higher.
An iPhone 5S, 6, or 6plus, will only update to iOS 12.5.7
iPhones 6S through 7, and SE(gen. 1), will currently only update to iOS 15.8
An iPhone 8 and later will update to 16.7.2
iPhone XS and higher will update to iOS 17.1.2
This support article has instructions about updating an iPhone or iPad wirelessly --> Update your iPhone or iPad - Apple Support Read the article for recommended criteria for being able to use wireless updating.
You can also use Mac and PC computers to update system software --> Update iOS on iPhone - Apple Support
If you want a video about doing this, follow this link —> https://www.youtube.com/watch/1FcE86kwODQ
When updating, your device will update to the highest version currently available that it will support, or it will just say it is up to date (and can't go any higher) and won't install anything. If you want to run a higher system version than your current device is capable of running, you need to buy a newer device.
For updating app software on a mobile device, follow this flow: App Store app > Updates, or select your icon in the upper right corner > click update all or scroll down past the first screen to select individual apps.
For updating hardware, click here to Compare Models --> iPhone - Compare Models - Apple
