When you lay it down (stand it up), it is in portrait format.
If you fold it to the side like an L, it is in landscape format.

Thank you very much for the feedback. I'm not sure if my question was clear enough. When you open the phone, the photos are in portrait format. Is it possible to switch to landscape format from this position, i.e. without moving the phone?

Both exactly

Both are possible, depending on the orientation of the smartphone, the photo would be created and saved in portrait or landscape format.