How to create a second Menu on a modular page

Hi I am still learning grav but it is amazing!

What I need is a way to click a primary nav item for example services. Then from here I can choose from the dropdown menu say hosting and I need to be able to go to a new page with a left side menu that still follows the navigation flow but shows up under services in a child page called hosting. The issue is the main site is setup in a modular structure and I am not sure how to go about adding a new page with a left side menu.

Any help or advise would be greatly appreciated.