[2021] Largest Possible world size?

The server size is limited by the three coordinates multiplied going higher than the maximum integer value. This means, the bigger the world is the more limited is the maximum height until it reaches a point where the maximum height is lower than the highest mountain to generate and the server hence crashes. The maximum supported size is 4km² (200 x 200), any size above will not get support when issues arise.

For a 4 km² world you want at least 16 GB of RAM if you plan on having an active public server, scaling beyond is not tested, as it's not supported.

There are no PvP mods to my knowledge. If there were, you couldn't find them on the official modding pages, though, as we do not endorse those.