The hardness of the light will generate dark shadows. The direction of the light will place those shadows in unattractive positions underneath the subject’s eyes and nose. One solution is to move the subject into the shade where he will be lit by skylight rather than sunlight. Skylight comes from a large source and is therefore diffuse. Diffuse light does not cast strong shadows. Skylight is also rather blue and, if you are using color slide film, you might have to place a warming filter (e.g., 81D) over the lens to get natural skin tone.
If your goal is to record a subject in front of a sunlit object then you can’t move him into the shade. There is too great a difference in illumination between shaded and sunlit objects. Photographic film and paper cannot handle the same range of contrast as your eyes. A picture that is correctly exposed for the sunlight object will render the shaded portrait subject as solid black. A picture that is correctly exposed for the shaded portrait subject will render the sunlit background object as solid white.
