Billy Bob Thornton wears Old Focals Classic sunglasses in Season 3 of Goliath (2019).

The glasses have a grey, square frame with two rivets on each side and front of the frame.

This style is inspired by the classic rectangular frames of the 1950’s and 1960's.

Made by Old Focals, a company that makes and provides eyewear for many films and series, you can still find this model in several color variations on the Old Focals website.

Reference: Old Focals Classic