The Steam Client has the ability to set Launch Parameters, commonly referred to as command line arguments, for games launched by Steam. If you find your self needing to set a Launch Parameter for a game, you can find the steps outlined below.
The first thing you'll need to do is locate the game in your library. After locating it, you can either right click the game entry in the sidebar or shelf, or you can click on the gear on the far right side of the game when viewing it as a page. All of these locations should provide a context menu similar to the one shown below with a
The properties context menu option should open a window similar to the one on the right, and you can find the
Launch Options header at the bottom of the window. Under that header is the field in which you can enter the Launch Parameters you want for this game. They'll be saved between restarts and will take effect the next time you start your game.