My kid is 11 years old. He want to stay in book store for a few hours. Is that OK

I don't know if it is against the law or anything, but personally, there is definitely worse things he could be doing than hanging out in a book store.

Is he allowed to go to the park by himself? Or to his friends house, does he walk to school alone?

Is he a mature 11 year old, does he have experience being alone, and dealing with strangers?

At 12 they are legal to babysit in some places here in Canada!

To me a lot would be location, Not sure I would want to leave one alone ( no supervision) for several hours in down town Atlanta, but would feel different in Sparta TN ( town of about 2000 people)

Why does he need to go to a bookstore for a few hours. Isn't that a long time to browse books of interest?

Is the bookstore in a mall?

If all he is doing is looking at books to buy, I'd say a half hour to forty five minutes should do.