Sex in movies for those over 16 is quite common. Even in the series. Just watch 15 minutes of Spartacus or Game of Thrones to find yourself with some extra skin.
Now, as you can understand, most of these scenes are not real, but it is simulated sex and, moreover, with body doubles.
However, from time to time, a director decides that in their films there can be no simulation. Here are some movies that used sex explicit rather than mock sex.