Those brightening products including chemical peels only useful for fading minor sun damage or acne marks (PIH). If you're born with naturally darker skin then it won't work.

That's sun damage already and not reversible unfortunately. You can start taking care now to prevent it from getting worsen, use SPF everyday when you're going out, at least 30+ SPF. If you're doing outdoor activities, you need to reapply sun screen every 2 hours.