Board Thread:ROBLOX help and discussion/@comment-29081836-20170524215154/@comment-31143516-20170525132346

its called letter resizing,

see that italic i in the bottom of your message box? thats the button to toggle italic lettering on and off.

i cant show you the code to make words small and large but if you wanna use it thenthis is the code on the wiki markup page.