Member areas: further gatekeep content from active members?

Site URL: https://wiscmartialarts.com

We use Member Areas as a way to provide curriculum content to our active members at our martial arts school.

Under the Member Area, we have all of our content broken down into different pages (one page per belt). Recently I have begun looking at ways to gate off each belt so that the full curriculum isn't open to anyone who has an account.

I am looking to see if the following is possible:

1. New member account can be created and access page for "White belt curriculum"
2. All other belt pages are blocked (some kind of an "Access denied" screen)
3. At our discretion we can open up additional pages to members after they meet certain criteria
4. Ideally this would be done on an account-by-account basis and not a general restriction

Any suggestions on how I can set this up?