No. Studies actually show that all people have the same amount of willpower at their disposal. You cannot train to have more or be innately endowed with more or less of it.

The difference between those that manage to stay lean or get lean opposed to those that don’t draws from two areas:

1) some people just have innately a huge appetite and some people innately don’t. For the second group their is just no willpower in need to refrain from eating all the time. This is the group of people that easily forgets to eat or skip meals because they don’t feel like eating.

2) Successfully resisting food temptations while having a huge appetite doesn’t consist in having more willpower but rather structuring your environment in a way that their is less need to exercise your willpower. It is much more costly in terms of willpower to not eat the gummy bears that are in your cupboard all the time than just not buying them the one time you’re grocery shopping. It is much more costly in terms of willpower to not eat at all or only have a tiny slice of a pizza than to eat a huge portion of broccoli (presumed that you like broccoli)

Being or getting obese is a combination of having great appetite and being confronted with calorically dense food options all the time. Just remove the exposure to the stimuli, than you will have more willpower stay on it.