Abs are just like any other muscle and need to be trained for core support. A lot of people will say abs are made in the kitchen and dependant on bodyfat, which is true, however building your abs will make them bigger and thicker, but again, with too high of a bodyfat % it won't show.
Anyway to answer your question, I have always gone for higher reps, lots of drop sets and explosive movement with abs much the same way I have with calves. My bodyfat is high enough to cover them and can only be seen when flexing although I am currently in a caloric excess and trying to build + it is heading into winter here so I am not fussed.
Keep in mind you can not spot reduce fat (as in no, you can not specifically remove fat from just your abdominal area and nowhere else. Fat loss is all round from the body and your abs are typically the slowest to drop fat in comparison to everywhere else).