I’m not entirely sure what this topic is about and what the ask is. We have advanced search, and we have intersection pages that can be reached by URL.
Maybe you’re wanting the Knowledge Explorer Plugin? I really like how that interface allows selecting multiple tags to drill down by tags. Can be seen here on meta: https://meta.discourse.org/knowledge-explorer.
The tags page is still fairly basic - as it is now we use it for managing tags but not so much for exploring and accessing discussions. It falls into disrepair regularly, and I often feel like hiding it from the hamburger menu and disallowing access to it by users entirely.
Maybe an upgrade would be to allow the knowledge explorer plugin to hijack the /tags route and so users can go there and start drilling down into the content as they see fit?