How can I update my iPhone?

You can update your iPhone by following these steps:

1. Connect your iPhone to a Wi-Fi network.
2. Go to Settings > General > Software Update.
3. Your iPhone will check for available updates. If an update is available, tap Download and Install.
4. If prompted, enter your passcode.
5. Agree to the terms and conditions.
6. The update will begin downloading. This may take some time depending on your internet connection speed and the size of the update.
7. Once the download is complete, tap Install Now.
8. Your iPhone will restart and the installation process will begin. This may take some time as well.
9. Once the update is complete, your iPhone will restart again.

Note: Make sure you have a backup of your iPhone before updating to avoid data loss in case of any issues...

Follow these instructions:

Update your iPhone or iPad - Apple Support

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If your phone is a first generation SE, then it can only be updated to iOS 15.7.4.