Scale

Scale is a command that allows you to modify the size of players. It's very similar to the command ingame, which does the same thing. Here's how it looks:

scale classId x y z

Examples

This will set every SCP-173 to be very long and wide, but short:

scale 0 2 .5 2

Because of its similarity to ingame commands, you should probably test out changing player's size ingame to figure out what numbers you'll set x, y, and z to.