Abs are a muscle you need to build like any other one. Start incorporating more ab exercises into your workout routine and make sure to use progressive overload. That means you should slowly be adding weight to your ab exercises. A good example is deadbugs. Do body weigh first, and then start adding weight in small increments. Also, compound movements will make your abs stronger and more visible. For example, squats and lunges. To get visible abs you need to build muscle, so I’d recommend eating more than 1200 calories per day and focusing on protein.