Help finding similar funcionality/theme/plugin

Hello! I’m new here so i’m sorry if it’s not the exact place!

I need to design a website with a sidebar with the same idea to the one appearing in this link: http://alliance.themerex.net/home-style-2/, titles, and the ‘plus’ button leading to submenus. I couldn’t find a plugin or a theme with a menu that clean, or maybe I’m looking in the wrong places 🙁
I’ve tried building something using Elementor (free version) but no success.
Any suggestions on where I can find something similar?

Thanks in advance!