you can’t spot reduce fat so you’re gonna have to lose weight overall. eat your goal weight in grams of protein everyday, and also make sure you are eating enough grams of fat. protein keeps you full, fat keeps you satiated. you also gotta eat at a calorie deficit to lose weight and tracking your calories helps with that. use my fitness pal.
you can also exercise for weight loss but it’s not necessary. i’d suggest walking 10k steps per day to burn more calories or weight lifting. weight lifting builds muscle (with high protein diet ofc) which helps your body lean out. not sure if you’re want a flat stomach or toned stomach. flat stomach = just diet, toned stomach = diet + excercise.