You can enlarge or reduce one or more selected features during an edit session with the Scale tool. In this example the features are scaled to fit a set of corresponding features free-hand. You can also use the F keyboard shortcut to type a specific scale factor to apply to the features.

Scaling features in this manner is not a common operation, so the Scale tool is not shown on the Editor toolbar by default. You can add it, and many other tools, to ArcMap using the Customize dialog box.