In most cases the plates are orientated on the horizontal direction in the detail, along the longest side. There are a few exceptions in the polygonal plate's case:
Just as is in the polygonal plate's case, the folded plates are displayed along the longest side.
The folded plate is created (in the modeling) by a main plate and the attached plate related with a bending radius. In the detail, the folded plate is orientated by the longest side of the main plate.
Using the "Set folded plate main object" command, you have the option to change the main plate and the result is different.
Regardless of the plate creation method in the model, whether created by the joints or with the plate creation options, the orientation in the workshop drawing follows the rules described above. In the overview drawing, the orientation depends on the user coordinate system.