Well you're on PC? It's very easy, just to MCPEDL.com and download a void world, then type in %appdata% on your search bar. Get to Minecraft>games>com.mojang>minecraftworlds 

Then copy the void world into your Minecraft World's folder.

If u want to make the game run 1000x better, install the sodium mod and the others from the same creator, also the ferrite core for memory management

If you create a superflat world, ther should be a preset that is exactly this

I am trying to make a void world without lagging my pc to death, so i can make a map, is there any way to make a void world without killing my pc.

Help please