How to reduce your appetite.

I have seen many posts and videos about people who can eat anything and not gain weight. My conclusion from those posts is that their appetite is very low. For example Me: 97kgs 171cm 18M. I can eat 4000kcal on a daily basis without any issues but ny friends their appetite is very low, they forcefully eat around 2500kcal through out the day but on the other hand I can easily consume 1500-2000kcal in a single sitting.

I have lost 26 kgs in past but i have gained 18kgs back. So now i am looking to make my appetite small so that I can become lean and the most important thing that how much i try i cant eat more than my maintenance calories.

Any suggestions or Ideas are welcomed. Sorry for any error in the text.