Create minecraft world with just one chunk?

I want to create a world in Minecraft where there's only ONE chunk means 16x16x256 blocks and the rest should be air but with worldborder that you can't fall down. So the world consists of just one chunk, how do I create something like this? Or are there already maps? Version 1.15.2 LG

Google helps:

https://www.minecraftmaps.com/survival-maps/1-chunk-survival

Then you can put barriers around or set the world border

Maybe this page will help you:

https://minecraft.tools/de/custom.php

Oh I missed that, thank you very much.