The simple answer is to act like an adult.
How you do that is difficult for a lot of people no matter what their age.
Do you take responsibility for your actions, or do you blame others?
Do you do the things you need to do without being prompted, or does someone constantly have to remind you to do them?
Are you honest about what you are doing, or do you hide it from others?
Do you handle your own finances?
Do you go out of your way to help others?
Are you on time for school, work, and appointments?
Do you do things on time, or do you make excuses for being late?
Do you have temper tantrums when things don’t go your way, or do you admit when you make a mistake?
Do you insist you know everything, or do you admit you still have a lot to learn?
I hope you get the idea from these suggestions, as they are just the beginning. When you show your parents that you behave like an adult, hopefully, they will treat you as one.
ps.. respect is earned, not demanded.