Improve quality of old photo

Hi,

I have at least two if not up to 10 old photos that have been digitalised (i.e. a photo has been taken of them by the latest iphone). I'd like the quality of these images improved if possible, especially the resolution. The two main images are attached below. The reason we want them improved is because headshots will be used for plaques on gravestones, which will mean them needing to have higher resolution as the images will be zoomed in on.