Simply put, yes. Ancient art provides a lot of evidence of accurate anatomical awareness of muscle development. Ancient warriors were expected to be able to carry, even run in some seriously heavy armor, cover long distances on foot, and did not eat fatty diets, so some muscular definition would only be natural.

Perhaps a more interesting aspect is the ideology of muscles in the ancient world.

Check out a statue like the Farnese Hercules. The guy is seriously muscled (the exact reality of the anatomy and proportions has drawn a lot of critical interest). But Hercules is kind of the dumb jock of ancient myth. He's meant to look strong, but not sexy.

The Apollo Belvedere shows another type and a phenomenon in depicting anatomy that can be seen in pottery, etc of a much earlier date. He's fit, but his arms aren't very muscular. Instead the focus is on his lower body with that oh so sexy v-line and super well defined legs.

Too much muscularity usually meant that you had to labor for a living, not a sexy trait, while seriously nice legs meant you ran a lot which was a leisure/sport activity. So you're more likely to see ancient art depict the more idealized/aristocratic body type, even if that did not reflect what people really looked like.