1. Add “tag” functionality for your WordPress website with the following instructions:
https://www.sitepoint.com/wordpress-pages-use-tags/
2. Add some tags to your pages:

3. Select both “Pages” and “Posts” for the “Post Types”:

4. Choose the tags previously applied to your pages:

5. Select your Pages to include in the Grid:

6. Add the “Filter” control to your Grid:

7. Select the tags to be included in the Filter Navigation:

Result:

Add Navigation Filters to Page-based Grids