basic page within a basic page
Well, I guess that you are asking about creating hierarchical menu structure, so that menu item pointing to your "another basic page" is a child of menu item for first "basic page"?

Then yes, there is a way, and pretty easy to it, when creating a second "basic page" and providing a menu link for it (in Menu settings section), make sure that you select your first "basic page" in Parent item dropdown.