WordPress comes with a standard set of roles and capabilities e.g.
- Super Admin ( only applies to multi-site networks )
These roles are described here https://codex.wordpress.org/Roles_and_Capabilities
However these are only the default, and can easily be customised to meet virtually any requirement.
Traditionally this has been a programming task, and many plugins will add new role definitions e.g. membership plugins will add members, e-commerce plugins will add purchasers etc.
If you are a PHP coder you will find the necessary functions in the codex e.g. add_role() https://codex.wordpress.org/Function_Reference/add_role
However, there is no need to go down this route if you don’t want to as there are several plugins that add a User Interface to WordPress roles & capability functionality.
My preferred plugin is called Members – see https://wordpress.org/plugins/members/
as it is easy to use and comprehensive in features