Create a flutter build xcarchive to build the archive. The archive can then be used for App Store submission. Essentially this would work exactly like flutter build ios except the archive build action would be appended to the existing xcodebuild flutter build ios command.

Split off discussion from #13065 (comment):

The value add from flutter tooling would be the creation of the xcarchive--that's what is going to use all the build settings, compiling dart/embedding frameworks/thinning logic. So a flutter build xcarchive command.
The last step of making the ipa is entirely specific to the developer and what they are using the ipa for, and Flutter can't and shouldn't assume any of the exportOptionsPlist values.