Lampshaded: "So you're Bob. I thought you'd be bigger."
Invoked: Alice says this just to mess with Bob or to test his patience.
Exploited: The Big Bad actually spreads stories about Bob being massive and exaggerates his feats. That way, when people meet him, they will be instantly disappointed and have little faith in his abilities.
Defied: Bob tries to become or simply look taller so he'll meet people's expectations.
Discussed: Bob and Alice have an argument on why she expected someone taller and if Bob is still tall despite her expectations.
Conversed: Bob and Alice are watching a TV show which hints at the appearance of a new Big Bad. After months of waiting, they see the new character and talk about how much shorter he is than expected.
Deconstructed: Bob tells Alice she was silly to assume anything about his height and that she was simply letting her imagination run wild.
Reconstructed: Alice retorts that size often correlates with feats of great strength, which Bob is known for, so it wasn't that far out of the question to expect someone taller.
Played For Laughs: Bob shows up and he is massive. Alice looks up at him and mentions she expected someone a lot taller, much to everyone's dismay.
Played For Drama: Bob feels inferior due to Alice's expectations. Meanwhile, Alice is disappointed and doesn't have as much trust in him.
Implied: Alice meets Bob and sizes him up then sighs to herself, seemingly disappointed but never says anything.