How To Enable Experimental Features?
Head over to the Game Panel and stop your server.
Navigate to the "Worlds" tab and click on "Edit" under the "Experimental Features" option for the world you prefer.
Select all the experimental features you're looking to enable. I'm running my server on Vanilla 1.21.3 right now, so I see 4 different options.
🎉 Congratulations, you've successfully enabled experimental features on your world. If you have any issues or concerns, please contact us through the ticket system.