Welcome to Forums. Thank you for using this space to share your thoughts. This is Juan from Zwift. With the latest changes, the workout library can be sorted by duration, elevation, distance, name, effort, and route completion. Do you mean something like a subcategory once you have already chosen category?
Anyhow, please feel free to share your feedback so we can continue to level up the workout library in the future. To share feedback, check out this post on our forums.