"Do sit ups everyday to get abs"
Sit ups DO NOT create abs! We all have abs we were born with them as they are part of our anatomy. The thing is that alot of the time these are hidden under a layer of body fat. Therefore the main way to see those delightful things is to strip away that layer of fat with your diet. I am not talking about going on a strict restrictive diet. I'm talking about eating in a slight calorie deficit with a nutritous well balanced diet. This is the most imporatnt factor as you need to strip away the body fat so focus on getting that first rather than stressing over doing endless crunches everyday!
Next up exercise - get lifting using compound exercises (squats, deadlifts, press ups, pull ups, bench) alongside some HIIT and some steady state cardio. You can add in a couple of ab focused sessions 1/2 a week as well just to target the areas you want to work on. But there are more than sit ups trust me
Lower abs - Leg raises (laying and hanging), reverse crunches, flutter kicks
Upper abs - crunches, V -sits
Obliques (side) - Russian twists, swirms, bicycle crunches
All over - Plank
Its a combination of a lot of factors to get them to pop and you need to do them all but remember:
You can't spot reduce fat
It takes time, hardwork and pesistance
Yes genetics do come into play and some people are naturally leaner but you can get them if you want them that much. But just a little note to finish on - There is more to life than having the perfect 6 pack and half the time it isn't maintainable all year round so be prepared for hard work if thats the thing you want.