You use "do" in your question when you are asking about something in general.
"Do you enjoy your classes with Anna?"
"Do you enjoy going to the park?"
You could possibly say "Do you enjoy eating that?" if you don't think it looks good and you are incredulous that someone is eating it.
You would use "Are you enjoying your meal?" if you are asking someone who is in the middle of eating. A waiter might say it to customers.