Spawn the Wither.

Using the Frost Walker boots, walk on at least 1 block on frozen water on a deep ocean.

Cure a zombie villager.

Kill a skeleton with an arrow from more than 50 meters.

Enter an End Portal.

Acquire 30 Emeralds by trading with villagers or mining.

Use Riptide to give yourself a boost.

Gather all 16 colours of wool.

Use a saddle to ride a pig, then have the pig get hurt from fall damage while riding it.

Activate a Conduit.

Place four Sea Pickles in one block.

Dye your bed a different color.