iTunes File Sharing
Some apps share their documents folder through iTunes file sharing. It’s up to the developer to enable this functionality. If this is enabled, you can find the app’s documents folder in Finder by selecting your iPhone in the sidebar and choosing the apps tab. Files can be transferred to your computer by dragging them to your desired copy destination.
Make a local backup of your device in Finder and use an app like iMazing to extract files from the backup.
If your device is jailbroken, you can access the file system with iFile and share files as you would files in the Files app (AirDrop etc).