Multiple roles/permissions

How can I implement multiple roles for a single user given the default config in this boilerplate?
e.g., I have a user account with the role `user`. `user` role has certain permissions e.g., `manageInvoices`, `getInvoices`. But I want one user to have the permission `manageOrganization` along with the rest of the permissions but I do not want to add `manageOrganization` permission to all the users who have `user` role.

Is there any way I can achieve this? Any ideas and suggestions are appreciated!

No file, test, or entry point is named. Locate the boilerplate's default role and permission configuration, then clarify whether per-user permissions or additional roles are intended; the work is done when the chosen behavior is specified and covered by relevant tests.

Written by the indexing model from the issue text.