Apple now stops signing iOS 12.0.1, that means the user can no longer downgrade to iOS to iOS 12.0.1 from iOS 12.1.
If you want to restore or upgrade your iPhone/iPad from iTunes it will now automatically update your device to the latest version of iOS that iOS 12.1.
Downgrading to iOS 12.0.1 not possible
Those who have accidentally updated your device to iOS 12.1 via OTA or iTunes, downgrading back to iOS previous version like iOS 12.0.1 is not possible.
Apple always gives older versions of iOS to restore whenever it releases a new version so that people can have the ability to downgrade their devices to the previous version if they are not satisfied with the new one or any issues. But after some time, it stops signing the previous version and allows the latest iOS version only.
You can also visit this link https://ipsw.me to check the signing status of Apple firmware.
Also, there are lots of users that are going to be affected with this change, specially Jailbreakers. The Jailbreak hackers usually work on to build a jailbreak on older versions and has successfully jailbroken on iPhone XS Max. So Jailbreak lovers who are on iOS 12.0.1, do not update to the iOS 12.1. But if you do not care about Jailbreak, you can upgrade to iOS 12.1.
The current and latest iOS version released by Apple is iOS 12.1 that comes with many bug fixes and new features. Check out the recent changes if you have not already.
We will keep updating everything new about Apple so keep checking iMangoss every day.