INFORMATION: METAL PHONE CASES DISRUPT THE PHONES ABILITY TO READ NFC TAGS.
If you have a Metal phone case, you may need to remove the phone from the case in order to read the NFC Smart Tag.
The iPhone XS (Max), iPhone XR, iPhone 11 as well as iPhone 11 Pro (Max) and iPhone SE (2nd gen.) models, feature “Background Tag Reading” function. NFC tags can thus be read automatically as soon as the iPhone screen is switched on without having to start the NFC Tag Reader first. The iPhone then looks for corresponding signals in the background. When a tag is detected, a notification appears on the display, prompting the user to open the item in the respective NFC app.
Just tap the top of the iPhone on the Smart Tag and you'll see this notification - Click to OPEN the App.
iPhone NFC Tag Reader is located at the top of the phone
This video shows where to place the iPhone when you want to read a Smart Tag