Clear all "pages" cache
If you enable the settings documented in example.settings.local.php then you can easily see the cache tags that are present on a page.

What you will see then is that each rendered node has the node_view cache tag, so you only need to invalidate that.

There's also the 'rendered' cache tag which as added to any render cached item.

I don't quite understand why your cache warmer needs to invalidate the cache first, shouldn't be a problem if it's already warm? Drupal will automatically invalidate something if it is no longer valid.

The internal page cache also has no time limit by default.