I needed to print our team hockey photo at Walgreens, but somehow I’d saved a cropped version of the team photo instead of the original — and these days Walgreens doesn’t let one print an image without cropping . Part of the image was cut.
My first thought was to custom print from Aperture to PDF then export a JPEG from that (it’s complicated) — but something funny happens with page orientation in Mojave/PDF.
The real answer was to use my old copy of Acorn (still works in Mojave). I resized the canvas to fit the horizontal image and fill in the right 3:2 horizontal:vertical orientation. Then I threw in a title for photo. Looked like it was deliberate.
 Once upon a time I think that was an option — just printed with white borders.