If you get your abs to grow through training then they will stick out more, making them more defined. There is tissue between them that gives them their six pack look. That tissue won't change or move.
Larger abs can give you a six pack even if you're holding a bit of extra fat.
Occasionally I do weighted DB crunches with a 100lb DB. I anchor my feet. I'll do sets of 10 or do 10 bottom half/10 top half/10 full with a lighter DB. From a "functional" standpoint this is probably pointless because I won't ever have to do trunk flexion against resistance. This is strictly for aesthetic purposes and it works for me.