Hi Charles,
One approach to create an Off Canvas Menu Like this is through a Block Element hooked to inside_slideout_navigation
.
Correspondingly, you’ll also need to turn on the Off Canvas Panel in Appearance > Customize > Layout > Off Canvas Panel.
Here’s a sample Block Element I created: https://share.getcloudapp.com/5zur7y8z
Resulting to something like this: https://share.getcloudapp.com/rRuOv6q6
You may use any Block you prefer to create the layout you wish.
In my sample, I used the WP Navigation Block to retrieve menus I created.
You can also simply use GB Headline Blocks and create each item one by one for more modification options.
Overview of the Block Element: https://docs.generatepress.com/article/block-element-overview/
Hope this helps!