They added support built into the camera app starting with iOS 11 (released in 2018).

https://9to5mac.com/2018/05/16/how-to-qr-codes-ios-11-iphone...

You can also generate them via Siri Shortcuts now, I wrote a simple shortcut that’s shown on the share sheet, so I can share WiFi credentials from 1Password via QR code.

The shortcut is just regex match the base station, password and security from the text 1Password shares, then format it as WIFI:S:<ssid>;T:<security>;P:<password>;; and then pipe that to the Generate QR code action.