You can do hours and hours of ab circuits but the harsh reality is if you’re not lean enough then you simply won’t see them. This is where the phrase ‘abs are made in the kitchen’ comes from.
Unfortunately spot reducing fat isn’t possible so ab workouts won’t ‘tone up’ the area you are hoping for. It will just be working the muscles underneath the fat.
So instead of spending hours crunching and planking, perhaps consider if your time is better spent elsewhere. For example, doing cardio to help burn some calories and lower your body fat percentage.