Warp7 framework itself does not support sub-level menu like that. The sub-level will be added below the parent menu item like this https://imgur.com/a/7PCm3

For this case, you can try FREE version of DJ Megamenu extension https://extensions.joomla.org/extensions/extension/structure-a-navigation/menu-systems/dj-megamenu-light/
Demo https://demo.dj-extensions.com/dj-megamenu/
Hover on second menu item (MEGA MENU – HOME) to see the effect right/left for sub-menu