I can’t update ios15
I want to update my iPhone iOS 15 but I can’t update and my Line can’t update
Question marked as
If your device is lower than iPhone 6S you can't update your device to iOS 15
Only compatible devices can be updated to iOS 15 or later.
iPhone 6S
iPhone 6S Plus
iPhone 7
iPhone 7 Plus
iPhone SE (1st Generation)
If you have iPhone 8 and above you can update to the iOS 16 or later
If you want to know more information read this article to understand better -> Update your iPhone or iPad – Apple Support (UK)