Header V8 is a pre-configured header layout of Konte. In order to select it, just go to Customize > Header > Header Layout and select Prebuilt Header as Header V8. With all header layouts, you can select header background, text color, set the height in the Customizer. Besides, the Topbar can be configured separately.
This header layout supports both the Header Main and Header Bottom sections. You can set the height and background, text color for these sections in Customize > Header. The height of the site header will be the total height of Header Main and Header Bottom.