Go to Settings > General > Software Update > Automatic Updates.
Turn on Download iOS Updates and Install iOS Updates.
When an update is available, iPhone downloads and installs the update overnight while charging and connected to Wi-Fi.
You’re notified before an update is installed.
To turn off automatic updates, go to Settings > General > Software Update > Automatic Updates.At any time, you can check for and install software updates.
1: Go to Settings > General > Software Update.
The screen shows the currently installed version of iOS and whether an update is available.
If there is an update, go ahead and proceed in the update.
For more information, please visit the link below:
https://support.apple.com/guide/iphone/update-ios-iph3e504502/ios