No not that, Essential Grid and The Grid are standalone plugins. Not an element of Cornerstone, of course, you'll get the Essential Grid and The Grid element for adding your grid on your page, but it has a separate panel for creating your grid.
You can install those under X > Validation > Extensions, look for the The Grid or Essential Grid whichever you want to use and install it.
Here's the official documentation of those extensions.
Extension - The Grid
Extension - Essential Grid
Hope this shed some lights,