The Advanced Search Results Page is provided with a sidebar that you can place on the left and right side of the web page. A sidebar in WordPress refers to a widget-ready area used by the website to display information that is not part of the main content but is displayed in a vertical column.
How to manage the Advanced Search Results Page Sidebar
In your left sidebar navigate to Appearance > Widgets and locate the Search Sidebar box as displayed in the image below.
As you will notice, there are Available Widgets displayed in the left part of the page. On the right side, you can find the Search Sidebar where you will need to drag and drop the widgets that you want to display on the page.