9to5Mac published a tutorial about how to customize Safari 14 start screen with wallpapers on macOS.

How to customize Safari 14 start screen with wallpapers on macOS

Safari 14 comes preinstalled with macOS Big Sur, and it will be available as a separate update for macOS Catalina later this year with new features and improvements. One of the most notable changes is the redesigned start screen, which features website suggestions and custom wallpapers. 

How to customize Safari 14 start screen with wallpapers on macOS - 9to5Mac