When selecting the Page Layout you have the options of Default, Elementor Canvas, Elementor Full Width, and Theme. Choose the best option based on the following usages:
Default – This uses the default layout including the Header, Footer, Content, and Sidebar. This may be controlled by the active theme, or the Elementor Theme Style and Global Template Display ConditionsElementor Canvas – This displays only the Elementor created content without the Header, Footer, Content, or SidebarElementor Full Width – This displays the Elementor created content including the Header and FooterTheme – This displays the predefined layout of the active theme. These options are generally found in the Customizer of the active theme
Note: Only posts that use the Default Template will have the Single Post Template applied to them, even if they otherwise meet the Display Conditions criteria. Posts that use Canvas or Full Width template (or any template other than Default) will not have the Single Post Template applied to them.