I decided to try using a neural network: https://bigjpg.com/ru
I use it to enlarge portraits; in art mode, small imperfections are lost, and the art becomes more like a fifth-level icon.
Here, this worked against me; the details on the shore disappeared, and the Academy became just a cobblestone (oh, lol, I'm an idiot – I put two images of the city with a fortress from the neural network in the comparison, and I put the original image of the city without a fortress… there doesn’t seem to be a cobblestone that looks like the Academy on the city with a fortress… it turned out awkwardly).