iPhone Xs, iPhone Xs Max and iPhone XR include a new feature for NFC that Apple didn’t mention on stage. The new models will be able to scan NFC tags in the background. With current iPhones, users must first launch an app to enable NFC Reader mode.
I have successfully used my iPhone X to scan my country’s ID card via NFC (in a banking App).
However, no background scanning on iPhone X.
iPhone XS and later support background tag reading.