The core Canvas product doesn't provide "prerequisite" controls for self-enrollment courses. In my experience, prerequisite course requirements are typically managed by the SIS that is integrated with Canvas.
If you have an SIS integration, you could see if there is a way to establish something like this through your SIS. If your school has the resources, you could also look into building your own custom integration to manage this. If you have multiple use cases for a "prerequisite" course requirement, you may also be interested in reviewing the Canvas Catalog add-on as this may provide the functionality that you need. How do I add a requirement to a Catalog program?
