However, for Midsommar, there were apparently specific instructions to actually walk in the woods before the scene, getting it all on tape.
Sometimes actors will be given specific lines to read on tape.
Taping yourself for auditions is a pretty standard practice.
Sometimes they have a bit more freedom to do whatever they want to try in order to show that they can handle the role, but either way, it’s usually just an actor and a camera reading lines.