Getting a chiseled midsection is mostly nutrition and losing fat, but training it optimally can help immensely in the process.
Abs are responsible for the transfer of energy throughout the body. If you can channel more energy throughout your abs, you’re likely going to be able to lift more, apply more force, jump higher, and run faster.

In that vein, building strong abs can help improve your performance. For a more physique-oriented goal, training your abs does have some benefits. The biggest being that, when you train your abs, those muscles will grow. When those muscles grow, they’ll start showing more, even at a higher body fat percentage.

That doesn’t mean that someone at 20% body fat who trains his abs should be expecting to get a six-pack. It means that as he begins dieting, he might start to see an outline of his abs at 15% vs. 12%. Is that a big difference? Not really, but it is a difference.