CJ, a poor gang banger from the hood, becomes a secret agent for an unnamed agency, then steals a jetpack from Area 51 to then steal Alien Goo from a government train convoy, and also ends up having to do a parachute drop to take back a Rappers mansion from a gang banging drug dealer he was in debt to.
Let's not act like San Andreas, and the entire GTA series, hasn't been ludicrous from the start even when they did went "grounded" for one entry. GTA VI may suck, but it's not going to be because GTA suddenly stopped taking itself seriously.