https://www.techradar.com/news/apples-iphone-xs-has-a-game-changing-nfc-feature-even-when-turned-off

The promise of using your smartphone as a metro card or an ID is often met with the response: 'Great, but what happens when my phone runs out of battery?'

The iPhone XS, iPhone XS Max and iPhone XR solve this legitimate concern with an NFC chip that works several hours after your new iPhone battery dies.