In a past article, I wrote about solving photo orientation problems that sometimes result when importing images. But that offered advice about fixing the rotation or other orientation issues before you imported into Photos.
How do you fix the orientation of a photo after you've imported it into Photos? The fix can be done in Photos for iOS and macOS, and if you’re using iCloud Photo Library, the change will percolate through all your connected devices. (iCloud.com has no option to rotate photos.)
How to rotate a photo in Photos for Mac
In Photos for macOS to rotate by 90-degree increments:
