You can setup automations using NFC tags with the shortcuts app to run automations that you program each tag to. For instance, you can create a shortcut to turn off your lights when scanning a NFC tag, send your ETA to a person, trigger a HomeKit device or you can use a NFC tag to start a Music playlist, etc. think of it like a programmable QR code.
Newer phones can scan a NFC tag in the background when you bring your phone close to the tag, it's always on. I believe on the iPhone X and some older devices, it's not always on so you need to turn on the function to scan the tag.