WHAT KIND OF AB EXERSIZES WILL DEFINDNITELY GET ME A NICE SIX PACK?

the reason why i ask this is because i already have a nice 4 pack dat i can see easy when i raise my shirt but i want 2 perfect what i already have into a nice six pack. i already do alota runnning because i play basketball and i go 2 das gym everyday day but i never really focused on my abs because i've always naturally had them. an honestly do crunches really work cuz some people told me dey dont