In 1976 or thereabouts the park service opened up Ellis Island to tours before the restoration work had begun. I took my trusty Nikon FTn and a couple of rolls of Tri-X and shot some stuff. I thought I'd lost the negs but they turned up by surprise last week.
In my experience, a developed negative may be scratched, grow fungus, or be damaged by water and chemicals. But the grain size will not change. That is, presumably, fixed in the gelatin emulsion. Remember, many films 40+ year ago were more grainy than what we have now.
And I didn't develop them, so I don't know how that was done. As I recall, they were developed and printed by a friend of my ex-wife; I don't know what developer he used, so maybe that's where the grain comes from. Nonetheless, it gives them a certain cachet...
You know, these photos remind me of some stuff I did many years ago when I first tried Rodinal. Similar grain patterns all right. Tried HC-110 after that and never went back. I took a look at the prints done (by the same person) from the second roll I shot that day on Ellis Island and they look pretty rough too. They looked better framed behind glass!