Well assuming you’re medically in good health, it’s really calories in calories out. Not saying changing your macros won’t have an impact, but it might not be the biggest fix. And you’d probably be getting more sleep if you could, so let’s just skip that. So it’s really eating a little less and exercising a little more/better. Generally people with visible abs and our age are usually a little hungry.
So on the calories out side, it’s changing how you exercise. How much is weight training? How long you going for/what’s the intensity? Cardio is valuable but more difficult for impacting weight loss if you’re already in good shape.
Personally I’m not joe 6 pack, but I did notice a substantial difference once I stopped ducking around 30 mins every other day and started doing a program from some trainer on YouTube.