She probably does better with older kids, because then it is not a "competition." When with her own age group... she is in "alpha" role.. meaning, the dominant/domineering position and tries to 'boss' others. Some kids are this way and some aren't. Kids also, like "older" kids, because it is fun and they like following the older kids around and doing what they do etc.
But... she is young. They don't yet know how to play socially nor reciprocally.
But I would 'practice' with her... because, once she is in preschool or in school... it may still be an issue and THEN she will be in a group with kids the SAME age. And then, other kids will get affected. In my daughter's classes and my friend's kids classes... there were 1-2 kids that were like that... and well, other kids don't want to play with them. Nor have play dates with them. Because they are bossy and bullying.
My friend's daughter, has a friend, that is like that. And well, my friend doesn't like when her child is bossed and 'bullied' by the friend. These girls are 5.
Again though, your child is young. They don't know socialization yet.
But in time, teach her. Because it will only benefit her. She will need to learn that... and especially in school, where there WILL be same aged kids.
all the best,
Susan