Read the step-by-step guide here: https://blog.logrocket.com/creating-multilevel-dropdown-menu-react/
You can download or clone this project by running this command from your terminal:
git clone https://github.com/Ibaslogic/react-multilevel-dropdown-menu
Then:
cd react-multilevel-dropdown-menu
npm install
npm start
You should see the app in your browser address bar at http://localhost:3000