There are 2 Sidebar Settings in our theme: Horizontal sidebar and Vertical sidebar .
Vertical Sidebar: Shows the sidebar with default style.
These changes are applied by changing the value of sidebar-layout property in the sidebar component.
If you like a particular type of sidebar and want to use that one in you website, then just copy the sidebar.scss file and add the necessary class to the sidebar-layout property in theme > src > Layout > ThemeCustomizer > Tabs > Sidebar > SidebarSettingsClass.tsx file.