Hey, @wakingland !
Ash here from the Shopify team. Thank you for posting your question in the Shopify Community Forums!
Creating a page that features a set of collections on it- essentially a collection of collections- is absolutely possible! We have a great guide right here which goes over step-by-step instructions for setting this up on your own store.
When it comes to making your collections that are created for a specific tag, it sounds like you’ll want to be creating Automated Collections. Automated Collections allow you to create collections of products that are automatically filled based on product conditions, such as containing a specific product tag.
With regards to automating this entire process, could you please reply back here and elaborate more on what exactly you would want automated? Are you referring to some sort of set up where you could schedule which collections are going to be featured on your page?
I’m looking forward to hearing back so we can continue to explore the rest of your questions together.