I’ve tested this with the tag set To value = 6. (which equals “Rotate 90 CW”)
https://www.exifTool.org/
I’ve used the exifTool To change the Orientation tag of an image like this:
"& '.\exifTool(-k).exe' -Orientation=…...converting MSG to PDF if msg contains (embedded) JPG with exif-tag...Family aspose-pdf-net , words-net , email-msg-to-pdf Christian_Bakke...