Issue facing installation of 12.4.4

If you're trying to do it wirelessly, see this guide:--> Get help with over-the-air iOS updates – Apple Support

If the issue still persists, update it usin iTunes on a computer. If you don't have a computer, borrow one from your friends, or ask for help at an Apple Store or Authorized Service Provider:--> Apple – Location Selector

Regards

Giulio

What have you Selected Install Now or Later? If you chose Later...

What did you choose Install Tonight or Remind Me Later. If you tap Install Tonight, just plug your device into power before you go to sleep. Your device will update automatically overnight.

Watch the GIF below