The theme offers to choose the location of the sidebar (left or right) or disable it. The theme offers to choose the location of the sidebar (left or right) or disable it. And you can choose how to display the header of a single post or page. To make it navigate to Customizer > Theme Options.
If there are no widgets in the sidebar, the sidebar will not be displayed.
If you choose an Cover header display mode then a size of post thumbnails should be at least 1200×860.
If you selected Cover mode for the Page Header display and upload a Header Image then the Header Image will not be displayed on the front page or blog page.