Each kid and their disposition and coping skills vary. And how a child is parented.
Kids this age are also typically in school.
Kids of this age are still learning. They don't have automatic inherent skills for social interactions, nor the ability to know absolutely what they are feeling or needing.
So, the parent helps in teaching them that.
It is like a rock collecting moss.
It takes time.
My kids are 5 and 9. I have had play dates for them, with 1 or more children, since they were Toddlers. They have done fine. Also because their friends, are compatible. And since 2 years old I have taught them the names for their feelings, how to speak up, how to know themselves etc. and how they can tell me. Kids need to be guided. Along with their age-related development and comprehension per age stage.
My kids have never been exclusionary or told a kid "I don't like you."
But yes, kids at these ages are NOT experts.... at social situations or in having finely tuned coping skills or communication.
Even Teenagers or adults, are not experts and "managing" all social interactions.