There are two main reasons why ancient Greek statues have small penises
Firstly, they’re flaccid. If you compare their size to most flaccid male penises, they are actually not significantly smaller than real-life penises tend to be.
Secondly, cultural values about male beauty were completely different back then. Today, big penises are seen as valuable and manly, but back then, most evidence points to the fact that small penises were considered better than big ones.
All representations of large penises in ancient Greek art and literature are associated with foolish, lustful men, or the animal-like satyrs. Meanwhile, the ideal Greek man was rational, intellectual and authoritative. He may still have had a lot of sex, but this was unrelated to his penis size, and his small penis allowed him to remain coolly logical. There are actually quite a few ancient Greek sculptures that have enormous penises. Here’s one:
|A Greek Terracotta figure of Priapus, © Christie’s 2015|
That is the end of the excerpt but there is much much more to be found in the full article (link).