Mark a design as a template
Mark a design as a template and choose which SKU data, rules and preferences and settings to preserve from it.
Mark as template (the design card's menu) first opens 'Advanced options': 'By default these values will be overridden from the admin settings. Choose what you want to preserve from the design.', with SKU Data, Rules, and Preferences and Settings to keep, then Cancel or Mark as Template.
Once marked, the card's menu shows 'Edit template settings' and 'Unmark as template' in place of 'Mark as template'.