Download: Managed App Schema Builder
Latest Beta: Beta
Before wasting time creating something that's already been done see if it's available:
Otherwise use the app to create a JSON file that can be used to set application preferences. Then don't be shy, if it's new please share what you have crafted.
Starting with Jamf Pro v10.19 you are able to create a custom schema, in the form of a JSON, to create a template for setting application preferences within the Application & Custom Settings payload (Computer Configuration Profiles).
Once all the keys and values have been set click 'Save'. The contents of the saved file will be copied to the clipboard. This can then be pasted into the Schema field in the Jamf Pro server.
The saved JSON file can later be imported and modify. Add/Update/Remove keys or change the description.
Thanks @talkingmoose for all the help!