One hit enderman farm

The classic enderman XP farm, designed by iJevin and built here by Shulkercraft. A ring platform 128 blocks out in the End funnels endermen towards a named endermite in a minecart, they drop into a chamber and one sweeping edge swing kills the lot. Carpet on the roof stops them teleporting out and iron bars hold the endermite in place. It costs about 22 stacks of blocks, most of the danger is in building it, and it has kept working through every version since 1.16 without a single change to the design.

The endermite has to come from a thrown ender pearl. One from a spawn egg does not draw the endermen, which is why creative tests of this farm fail.
Take Thorns armour off before you spawn the endermite or you kill it the moment it hits you. This is the most repeated mistake on the video by a distance.
Name the name tag on an anvil before you go up, and wear a carved pumpkin so you can look at endermen while you work.
Do not build any of it out of dirt or anything else endermen can pick up. They take it apart.
Do not send the ender pearls into the void. They do not despawn down there and the chunk fills with entities and lags. Drop them in lava instead.
Water does the job of most of the carpet, since endermen will not teleport onto waterlogged blocks either.