Can I update my IPhone 6s

Hello,

There are different ways to ensure the highest iOS that your device will support is installed on your device. For an iPhone 6S or 6S Plus that's iOS 15.7.8

This support article has instructions about updating an iPhone or iPad wirelessly —> Update your iPhone or iPad - Apple Support

You can also use Mac and PC computers to update system software, as described in this article —> Update iOS on iPhone - Apple Support

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 will run, that you need to buy a newer device.

If its an actual iPhone 6s you should be able to update to iOS 15.7.8.

If its an iPhone 6 (no s) then it cannot update beyond iOS 12.5.7. That is the last version it supports.

iOS 14 is no longer available to update to. If your iPhone currently has iOS 14 downloaded, it will be unable to update to it, as its no longer verified for update. You will need to delete that update from Settings ➜ General ➜ iPhone Storage and try to download a newer verified version.

If it still won't update, you may have to connect it a computer and update it using iTunes or the Finder.

click here ➜ Update your iPhone, iPad, or iPod touch with iTunes - Apple Support