The ModZer0 Minecraft DNS teleport dance.

1. clear player Enderchest using replaceitem
   replaceitem entity @p slot.enderchest.#
   (or not, since it was removed in 1.17 - so use item command
   item replace entity @p enderschest.# with air
   Although, this means I need to iterate and do that for all 0..26 slots? It appears so.
2. clear player inventory
   clear @p
3. reset target spawn area chunk
   possibly use the clone command
   clone from <sourceDimension> <begin: x y z> <end: x y z> <destination: x y z>
4. reset player spawn to new world spawn location
   spawnpoint
5. teleport player to new spawn location
   tp @p $WORLDSPAWN

OR

We do the crazy thing Walker figured out using command blocks.