We've all been there. You've just finished a great workout, went and took a shower, and then for whatever reason, decided you wanted to see the whole leaderboard for that class. The good news is - yes, it's possible! The bad news is, at time of publishing, it's not possible through the app.
To view the entire leaderboard for a workout after a class is over, (whether it's a ride, run, bootcamp, or other class style) simply go into your profile on your Peloton Bike or Tread (or Bike+ or Peloton Tread+). Find your workout history, and click on the class you want to see your ranking or full leaderboard of. Once you have the details open, there should be a button to View Leaderboard next to your rank. Clicking that will take you back to the full leaderboard that you can browse and review however you want.