For pages at level three and below in your site structure, use the Sidebar Navigation pattern as the first block at the top.
How it works
This will place a dynamic sidebar menu onto the page to make sure users can access pages that aren’t included in the top-of-site menu. The Sidebar Navigation pattern populates based on the structure you assign to each page in the “Parent” field, either inside the Page settings menu when creating or editing the page, or from the Quick Edit in the All Pages view of the dashboard.