A friend of mine, who is local to Japan, noticed someone from abroad with a folding map who looked lost, and would like to know whether or not she could say "Can I help you?".
She had overheard the expression "Can I help you?" while inside stores, but she doesn't know whether it sounds natural for English speakers. Is it natural? Does it matter that she's not a staff member being paid to provide a service? If not, are there better alternatives?