Apple just locked the iOS 12.2 sign , of course the entire update from 12.2 or below. Users after upgrading to iOS 12.3cannot restore the old version as well as the official version 12.3 is the only option.
I recommend you are in iOS version 12.xx (which is not 12.3), so upgrade to the highest version because every Apple update is a lot of fixes, iPhone 5S is also comfortable.
Apple is testing the beta for iOS 12.4, supporting the upcoming Apple Card this summer.
