I can’t install my iPhone iOS

VPN or proxy connections might prevent your device from contacting the update servers.

• Get help with over-the-air iOS updates - Apple Support

• Remove and download the iOS update again

If you still can't install the latest version of iOS, try downloading the update again:

1. Go to Settings > General > [Device name] Storage.

1. Find the iOS update in the list of apps.

1. Tap the iOS update, then tap Delete Update.

1. Go to Settings > General > Software Update and download the latest iOS update.

If you don’t see the update in the list of apps or if the issue happens again, you need to update your device with iTunes.

Try updating iOS after each step.

• Try to Forget the WiFi network and add it again

• Try another WiFi network 

• Toggle sets automatically off and then on

• Reset your network settings

• Force restart your device

• Remove any beta profiles, if applicable

• If everything fails: - Use iTunes or Finder (for macOS Catalina+) to update your device instead of over-the-air

• Get help with iOS update and restore errors - Apple Support

• If you see an error when you update or restore your iPhone, iPad

You need a wifi connection to download software, storage for installing software and at least 50% percent battery to download and install software..otherwise it will not downloaded/installed..if there are any VPN connections, that might prevent you from update..

check all facilities to update your iOS..

link:

Update your iPhone, iPad, or iPod touch - Apple Support

Your specs say you're running iOS 13. If that's true, you will most likely need to update using a computer.

Update using your computer -

Update iOS on iPhone - Apple Support