This repo contains random example files in random state of up-to-dateness.
Two of these spawn you in a completely empty void world. Be ready to fly and /setblock ~ 0 ~ stone.
Height from 0 to 15: https://github.com/onnowhere/examples/raw/main/16_height.zip
Height from 0 to 511: https://github.com/onnowhere/examples/raw/main/512_height.zip
Height from -512 to 511: https://github.com/onnowhere/examples/raw/main/negative_height.zip