Adding an eSIM to an iPhone with a QR code is now possible starting with iPhone XR, XS and future models. All supported devices.
But I only have one device!
The only difficulty you might have is if you do not have a 2nd devices which can display the QR code. In this case, simply find any human being with a smart phone, and ask them if they would be nice enough to take a photo of your QR code, so that you can then scan it into your own phone.
Once a QR code is ready for scanning, just open Settings -> Cellular –> Add Cellular Plan and then camera app will open, ready to scan any QR codes it sees.
You’ll need to be on wifi or have an internet connection in order for the eSIM module to make it’s connection to the carrier, but after that, the SIM profile should be loaded and you’re able to connect.
If you’re on a roaming plan where the the roaming SIM may activate if you are in one of the roaming countries, you may want to wait for the right time to load and active your eSIM – usually right before your trip.
Also keep in mind, eSIMs are designed not to easily switch phones, so in most cases, you’ll need to get a new one with a new phone.