ἐν μεγέθει γὰρ ἡ μεγαλοψυχία, ὥσπερ καὶ τὸ κάλλος ἐν μεγάλῳ σώματι, οἱ μικροὶ δ' ἀστεῖοι καὶ σύμμετροι, καλοὶ δ' οὔ.
Nicomachean Ethics 4.3, 1125b6-8
For greatness of soul depends on scale, just as a beautiful body must possess a certain scale, and small people are neat and well-proportioned, but not beautiful.How small is 'small' here? It's not clear. Perhaps it's like one of those signs at the fairground: 'You have to be this tall to be beautiful'. He's consistent, at least. I suppose this is a bit like him claiming elsewhere that some animals are too small to be beautiful because you see them all at once (and some are just too long to be beautiful). And I suppose it is true that some pieces of music or some plays might be too short to be properly beautiful since they cannot display the kind of organisation and structure that takes time to perceive (Poetics 7, 1450b35–1451a10 and 23, 1459a17–21).
It's a shame we don't know more about Aristotle's own appearance. Diogenes Laertius (5.1) says that Aristotle had slender calves ('so they say') and small eyes, wore lots of rings and a conspicuous hair-do.