QR reader on Android [built-in]
If you are using Google Lens on your phone than this gonna be very useful for you.
There is an built-in QR code scanner on Android. It works inside Camera app when Google Lens is activated.
If you still don't haven't it on your phone go and grab it from Google Play
Lens will be found anytime via icon on lower right corner when Assistant is on use.
I have OnePlus 6 and it is in left corner when you launch app and it is easy to use it.
Here is example from my device of Wiki page for QR Code