I have a 4 yo boy who is like this. He even tells me "that's not how it goes" when I sing a song differently. (I sing "4LM were jumping on the bed, dck fell off...diff dck called "my name" etc or patty cake, "mark it with a K for the kids and I")

I just remind him that we are all different and we can do and play things with they way we like as long as it isn't hurting our friends. I also tell him that if he only wants to play his way than he will have to play by himself because his friends don't want to do that and I don't want to listen to fighting. It usually works and he will play nicely. I have 2 kids who are only children and they actually free play nicer than the 2 with siblings lol. It's definitely a personality trait with those 2. They do know how to play with their friends when I speak to them about it but they would rather play with them being the "boss"!