The update has didn’t installed

If your iPhone's iOS update is stuck on the downloading screen, you can try the following steps to fix the issue:

1. Restart your iPhone: Press and hold the power button until the "Slide to power off" slider appears. Drag the slider to turn off your iPhone. Then press and hold the power button again until you see the Apple logo.
2. Check your internet connection: Make sure that your iPhone is connected to a stable Wi-Fi network with a strong signal.
3. Free up some space on your iPhone: iOS updates require a certain amount of free space on your device in order to be downloaded and installed. If you don't have enough free space, the update may be stuck. You can try deleting unnecessary apps or files to free up some space.
4. Wait a while and then try again: Sometimes, the App Store servers may be experiencing high traffic or other issues that can cause delays in the download process. If the download is stuck for an extended period of time, try waiting a while and then attempting to download the update again.

If none of these steps help, you can try restarting your router or contacting Apple Directly.