Computer Configuration > Administrative Templates > Microsoft Edge
Both
HKLM\Software\Policies\Microsoft\Edge
DEPRECATED: This policy is deprecated. It is currently supported but will become obsolete in a future release. Control the presentation of full-tab promotional or educational content. This setting controls the presentation of welcome pages that help users sign into Microsoft Edge, choose their default browser, or learn about product features. If you enable this policy (set it true) or don't configure it, Microsoft Edge can show full-tab content to users to provide product information. If you disable (set to false) this policy, Microsoft Edge can't show full-tab content to users. This is deprecated - use ShowRecommendationsEnabled instead.