Set boundaries and stick to them. She needs to understand that what you say goes. She is also trying to establish her autonomy, "Hey look I'm a whole other person not mom or dad so look what all I can do!" You have to realize they have not experienced the world much and this is how they learn what is acceptable and what is not. Give her tasks that are JUST hers that she can accomplish all by herself. She'll gain confidence and be focused with that energy. But, again, boundaries are key.

If she throws a tantrum in public I say bye I'm going home. She stops immedietly. But normally I do time out or pop on the hand or butt and look her in the eye and calmly talk to her.

I do time out chair, pops on the hand, time in her room, pops on the butt (that’s if she did something to her sister)

Time out; she’s 2, so she gets 2 minutes of time out..