Use by running /toastyshrink ingame. A simple Fabric mod (currently for Minecraft 1.16.5) that reads Minecraft commands (one per line) from the config file (in %GAMEFOLDER%/config/toastyshrink.cfg).
There's no need to restart the game after changing the config file because it is re-read every time you execute the /toastyshrink command.
Allow cheats must be on to use the command.