This is a fast and sample Flutter augmented reality example tutorial. I tried to fixed the issues encourted. And you can find them in issues. Hope it will be useful for your work.
ARKit is the best plugin for iOS device, and I don't recommend you use the ar_flutter_plugin, which have a complicated configuration process. Here is the tutorial to set up.
Make sure uncomment the 'platform :ios, '9.0' in the iOS/podfile and replace the '9.0' with '13.0'
Run with 'Flutter run --release'