Approaching the topic of first date sex can be extremely tricky. One way is to be very honest and open about your own boundaries and intentions early on in the date. For example, you could say something like 'I'm really enjoying getting to know you, and I'm not looking for anything physical tonight.' This makes it clear where you stand without being judgmental of the other person's potential views.
The best approach is probably to let the relationship develop naturally. Instead of directly approaching the topic of first date sex, focus on building a connection. Share stories, laugh together, and find common interests. As the date progresses, if there is a mutual physical attraction, it will become more obvious in a more natural way. There's no need to rush into discussing sex on the first date when you can first establish a good rapport.
If you're thinking about bringing it up, try to read the other person's signals first. If there are some flirtatious but non - sexual conversations going well, it might not be the right time to mention sex. But if the conversation is veering towards more personal and physical topics, you could gently ask 'What are your thoughts on taking things to a more physical level on a first date?' This gives the other person an opportunity to share their perspective.