To optimize your Landing Page for search engines, you need to add appropriate Title and Meta tags to it. The option to add this information can be found both within the Builder as well as in the Dashboard.
NOTE - This is a page-level setting. i.e You can have one set of Title and Meta tags for one of your landing pages and this cannot be changed for each of the Variants for that landing page.
In the builder - Navigate to Global Settings Panel > SEO
In the Dashboard - Navigate to the tab Settings > SEO within the respective landing page.