The Contextual Navigation is a vertical side navigation that displays in the right column of a two-column layout. The component is a list of all child pages under a selected parent page. Navigation items are automatically selected and displayed based on the starting point in the site hierarchy.

No, the Contextual Navigation only includes the page titles.
A Two Thirds Page is a two-column page layout. The two-column design applies to all page content.
In Page Builder:
Alternate method:
A Contextual Navigation component can also be used in a Two Thirds Sublayout. This two-column container applies to the section of page content added to the container. The Contextual Navigation can be added in the narrow column on the right.
In Page Builder:
Alternate method:
There have been reports that a Contextual Navigation component can be unresponsible to selection in Page Builder once added to the page, making it a challenge to access the component options menu.
To select the Contextual Navigation component on the page in instances where clicking the component does not suffice: