There's a better way than Slipknott's AMS, and that is CCOA's UMS (Universal Message System) that is attached to this post in a demo. To get the script, go to the Game Editor, then go to Script Editor -> UMS and copy everything there, then past it into a new script above main in YOUR script editor. Then, to make it fit as small as possible, input the following code into a "Call Script" event before any of your text:
$game_system.ums_mode = FIT_WINDOW_TO_TEXT
That will take care of it. The reason this is better is because this won't make you have to retype everything for the text to show up like in Slipknotts :bean: