Feature Request: Add a Menu Horizontal Separator Option

Sounds like a good idea. But on what basis do you build your menus? Themes often determine the look (the direction). Are you still using the classic menu under Design > Menus or are you referring to a menu in the Side Editor?

To file a feature request, please follow https://core.trac.wordpress.org/newticket and choose “Feature request” as the report Type. For more see https://www.wpbeginner.com/beginners-guide/how-to-make-new-feature-suggestions-for-wordpress-beginners-guide-to-using-trac/