The admin console exists within the workspace and let's you control access and privileges for that specific workspace. An existing admin can get to it from the drop down in the very top right and selecting Admin Console.
The first screen you'll land on is the user management pane. Here you can add/invite new users via email (if you haven't set up an SSO IdP to manage this) and more relevant to your question, there's checkboxes next to each user where you can select whether they are admins or not. Granting admin access gives users the ability to see all folders/notebooks and manage/edit/create any clusters or jobs.
If you are a SQL analytics user, this is also where admins can allow or deny folks access to either the standard Databricks workspace or only the SQL analytics workspace.
