Hi there’s an app called QR reader. It’s okay I guess, it does it’s job just fine just nothing special. Bellow I’ve provided the link of the app I use.
https://apps.apple.com/us/app/qr-reader-for-ipad/id426170776
I hope this helped! Have a great day!
https://blog.qrstuff.com/2012/12/28/qr-codes-for-app-store-downloads