Depends on what you want to know. Don’t ask questions with the intention to get a one-up. Don’t assert superiority from the get go. People can’t be defined easily using simplistic labels.
Here’s what I do. I ask them to state clearly what they believe. Then I ask them why they believe it.
These two queries will lay a solid foundation for debates and conversations that may follow. And they work when debating any view, not just Biblical literalism. Bear in mind however, that you need to be able to answer these questions yourself too. You need to be able to clearly state what you believe and why you believe it.
Often, you will run into people who can’t answer questions clearly or are evasive. Explain to them that you are asking so that the debate is fair and so that you don’t end up misrepresenting their viewpoint. If they can still not answer, form smaller, specific questions with examples so they can follow.