Don't Install iOS 12.4.7 If Your Situation is Fluid
If you're hunkered down at home trying to weather the Coronavirus, if you're a first responder that uses your phone, or if you are you unable to spend time on the phone with Apple if something goes wrong after the update, you should wait to install this update until a later date.
There's a good chance iOS 12.4.7 works fine on your phone or tablet, but it takes a while to install the update and there is a chance something could go wrong.
The last thing you want to deal with right now is waiting an hour for an update to install, finding help with Apple Stores closed, or dealing with apps or services that aren't working.
If any of these things concern you, you might want to hold off until we know more about iOS 12.4.7.