It depends on where the data is stored. If it's stored on the device, you may need to copy the data from your iOS device to the storage location on your Mac and vice versa to keep them synced. For example, I have a game that stores data in On My iPad. I can upload the folder to iCloud Drive, and download it to my Mac's user > .config folder. That folder is hidden and can be unhidden by using Command Shift + . I tried it for a few days but decided it wasn't worth the effort.
If you'd like to be more specific about the app and its data storage location, we might be able to give you more specific help.