Congratulations on your new iPhone X! I'm sure you're excited to use it, but I see in your post that you are having trouble performing certain tasks, like updating your iOS, becuase there is an iCloud backup still attempting to restore. I'm happy to help!
Based on what you've described, I would recommend using the steps provided in If iCloud Backup couldn’t be completed or you can’t restore - Apple Support , which will walk you through troubleshooting.
Thanks for visiting the Apple Support Communities! Have a lovely day.