Although Cobra Kai may be full of action sequences, there is also some deep symbolism found, such as the book Robby was reading when he was in jail in season 3. Deprived of a comfortable upbringing, Robby had to go through a lot of struggle to make ends meet, even prompting him to the point of breaking the law. Appearing as calm and mature in some scenes while also showing his hot-headed aggression at times, Robby makes for an interesting character study in Cobra Kai just like his own morally gray father. So, even when he spends most of Season 3 in jail, he still doesn’t come off as an inherently evil character.

https://screenrant.com/cobra-kai-what-book-was-robby-reading-in-jail/