Way 1: Run iOS System Recovery
For many iPhone users, finding out the real cause is a hard job. If your iPhone is free from physical damages, you can run Apeaksoft iOS System Recovery to take iPhone back to normal without data loss. Different from common iPhone troubleshooting methods, the program can detect and fix iOS system glitches automatically. You can get your iPhone to finish restoring from iCloud backup within a few minutes. No iOS data or settings will be replaced or erased. So you can feel free to fix old and new iPhone stuck on updating iCloud settings.

Way 2: Force Restart iPhone
You can force restart iPhone when iPhone is frozen or disabled. It is a safe way to reset and remove iPhone glitches.

Force restart iPhone 8/8 Plus/X and later: Quickly press and release the Volume Up button. Then repeat this operation on the Volume Down button. Hold and press the Side button until the Apple logo appears.
Force restart iPhone 6s/6s Plus/SE: Hold and Press the Sleep/Wake and Home buttons. Release two buttons when Apple logo appears on the iPhone screen.

Way 3: Check Wi-Fi Connection
Make sure you enter the correct Wi-Fi password. If you are not sure, you can reconnect to a new Wi-Fi network.

Step 1 Open the Settings app.

Step 2 Choose Wi-Fi and select the preferred wireless network.

Step 3 Tap Forget this network followed by Forget.

Step 4 Reconnect to a reliable Internet connection.

Way 4: Skip iCloud Setup
After updating iPhone, you will be lead into the iCloud setup screen by default. You can skip the Sign into iCloud screen by choosing the Cancel option. It is also a good way to fix iPhone 6s stuck on updating iCloud settings.

Way 5: Check iCloud Server
You can check the Apple system status list to see if iCloud is available or not. If there is a green icon in front of iCloud service, it means iCloud works normally.

Learn another 3 ways and detailed steps from this article:https://www.apeaksoft.com/fix/iphone-stuck-on-updating-icloud-settings.html