In the current react-play, you can't have the play outside the main application as it is coded in src/plays.
Nevertheless, it's possible to build the application with the plays in another folder by using create-react-plays as it is the foundation for play creation.
The current react-play doesn't allow it and the cost to move the application in the right way is heavier because lot of modification are needed and the validations are too slow.
A way to move the plays outside the body is needed and a better way to load plays too for performance issue.