This glitch can be done using creative mode.

If you'll set a portal block in the end dimension using commands and try to teleport to the another dimension, you will be sent to the overworld really high (32765Y) and will be stated as dead. Death screen will not appear and you still will be able to move but you can't break/place blocks, can't get hurt, can't attack anything. can't use some commands, mobs will not spawn and will be gone (Even you will not get damaged in any way, (commonly hitting the ground too hard) Mobs will still not interact with you), can't interact with chests, fall infinitely below bedrock during this giltchy state.

The only way to get rid of this bug is to quit the world, then you will be sent to the spawn point after re-entering the world.