Going off "510M sq/km" for the Earth's surface area, that gives you about 7 blocks per sq/m. You could drop down to 2x2 blocks per sq/m to give you a 50cm resolution (good enough, I reckon).

But the vertical resolution is awful. Sticking to ~sea level and modelling Everest, you'd get 23m/block which is useless for most things building-wise. If you wanted the Mariana Trench as well, you're down to 50m/block.

(You can change these in your `server.properties` but I've no idea what breaks.)

Bedrock is default 60000000 x 60000000 x 60000000 which gives you the 50cm horizontal resolution and (I think) ~0.3mm resolution vertically.