AutoCAD's Scale command is a tool that lets users scale an object uniformly (X, Y & Z scale at once). First initiate the scale command, next select your base point from which to scale from (I choose a first point of the side of my object I wish to scale), then input "R" for Reference, select reference points to define the length of the object you want to scale (I first choose the aforementioned first point then choose the second end of the side of my object I wish to scale), and finally I'll click a third point which stretches the first and second reference points of the side of my object to now be the length from base point to this third selected point -- or new length.
Here's a link I just googled for Scaling by Reference.