Since Trimble no longer lists 21.0.0 as the default download on their main site (as of 2025), here is the official method:
: This was a major organizational update allowing users to group multiple tags into folders. You can control the visibility of all tags within a folder simultaneously, making it much easier to manage complex models. sketchup 21.0.0
No .0 release is perfect. Here are the top three bugs reported in version 21.0.0 and how to resolve them: Since Trimble no longer lists 21