Open Settings
Tap General
Tap Software Update
If the update is downloading, tap Pause Download or stop the download if available
If the update is already downloaded, tap Delete Update
Go to Settings
Tap Wi-Fi
Turn off Wi-Fi
Go to Settings
Tap General
Tap Software Update
Turn off Automatic Updates
Tap Download iOS Updates off
Tap Install iOS Updates off
Go to Settings
Tap App Store
Turn off App Updates if needed
Enable Low Power Mode if you want to reduce background update activity
Avoid connecting to Wi-Fi and power if you want to delay automatic installation
Restart the iPhone if the update keeps trying to resume
If needed, use Screen Time restrictions to block changes to account or settings
If the update is stuck, connect to a computer and use Finder or iTunes to manage the device update prompt