There is block type called Classic which emulates the old WP editor. Classic type can later be converted to modern blocks.
In the Right Sidebar there is a ‘map’ widget, which shows because the widget’s visibility is set to: Display if Page is Equal to Front Page (Home page is the Front Page, or landing page).
One could reverse this logic by declaring that a widget be displayed only if the page does not equal front page. Then, the widget (and the Right Sidebar) would appear on all pages except for the front page. There are other logical recipes for when a widget should show or remain invisible.
The Right Sidebar will only display if there are widgets that are set to appear there. For example, a widget might be declared to display on the donate and bikeracks and welcome pages — and not on other pages. The other pages will not have a Right Sidebar. This then creates a full-width layout, which favors a large banner image or map.