The battery health feature is only available for the iPhone 6 or later. You would have to use other methods to determine the health of your iPhone 5S battery. If you have a Mac, you can download CoconutBattery. it will give you the battery health of your Mac battery and any iOS devices connected to your Mac. coconutBattery 3.7.2 - by coconut-flavour.comI notice when people are selling their iphone or asking questions they sometimes mention that their battery is XX% healthy.
How do I go about establishing the current health rating of my 5s battery?