This is a very simple mod for the game Lords and Villeins.
It allows defining a custom world size which will be used when a new game is started.
You can set your desired world size in the mod's config file under [Game Directory]/BepInEx/config.
This mod is based on BepInEx. So you need to install that first: https://docs.bepinex.dev/articles/user_guide/installation/index.html
Download the latest release of the mod and place WorldTweaker.dll in your BepinEx plugin folder.