How Do I Upgrade to a Specific iOS?
Contents by Alt-Clicking on the Update-Button in iTunes You Are Able to Select a Specific Package You Want to Update From. Select You Downloaded Package and...
By alt-clicking on the update-button in iTunes you are able to select a specific package you want to update from. Select you downloaded package and wait until the software ist installed on the phone. You should be able to install the most recent version of iOS for your iPhone model this way.
Can you choose what iOS to upgrade to?
Yes, it is possible. Software Update, either on the device or via iTunes, will offer the latest version that is supported by your device.
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How do I update my iPhone to a specific iOS?
Customize automatic updates
Go to Settings > General > Software Update. Tap Automatic Updates, then turn on Download iOS Updates. Turn on Install iOS Updates. Your device will automatically update to the latest version of iOS or iPadOS.