A customer wants to change the layout of the out of the box Order Summary...

The bestway for the administrator to satisfy this requirement is to edit the Lightning Record Page and change the Template to Three Regions. A Lightning Record Page is a type of page that displays details and related information about a specific record in Lightning Experience or Salesforce mobile app. A Lightning Record Page can be customized using the Lightning App Builder, which is a tool that allows administrators to drag and drop components onto a page layout. A Template is a predefined layout that determines how components are arranged on a page. A Three Regions template is a type of template that divides the page into three columns or regions. The administrator can edit the Lightning Record Page for the Order Summary object, and change the Template to Three Regions in the Lightning App Builder. Verified References: https://help.salesforce.com/s/articleView?id=sf.lightning_app_builder_customize_lex_pages.htm &type=5https://help.salesforce.com/s/articleView?id=sf.lightning_app_builder_templates.htm &type=5