Taking the legal age out of the equation, when do you personally feel someone is an adult, if you can pin point an age, what age would that be?

Would it be when they take on certain responsibilities? When they can start doing ”adult” things (like driving, sex, drinking, etc), and if so what specific things?

Just the other day I saw someone on this app say ”by 21 youre a full grown adult” and a lot of people said back ”i would not really consider 21 an adult”. I've also seen people say ”by 16 your pretty much an adult since you can drive and consent”. By the time I was 15 my dad considered me an adult because I was living alone and had taken on most responsibilities. But just the other day I was told I wouldn't be an adult till I graduated from college. When I was 17 I had someone consider me and an adult but someone a year older than me, not an adult.

What is your opinion?