Thanks for reaching out. We're happy to help. As the scanned image you have attached is pixelated and grainy, we need to check out the following video tutorials to understand how we can make it look better.
Firstly check this video which shows how to convert a low-resolution image to a high-resolution image.
You could convert the image to a Smart Object, and run the Dust and Scratches filter on it. It will look rather soft. This will add a mask for the Smart Filter. Paint on the mask with a soft black brush (Airbrush mode helps) over the facial features and hairlines, just enough to bring the detail back out in these areas.