Google Cultural Institute is just plain awesome. SUPER high res photos that let you zoom in to your heart’s content. Right now in the front page you can color in hokusai’s great wave. You can explore lots of famous museums using google street view. It’s really incredible and totally free.
If you want to bulk save high res artwork of artists, not sure tbh. I’m certain there’s a way to download the high res images on GCI though
artsandculture.google.com/asset/…/rQEx7CtGiKE3yghere’s a good example. You can zoom way in and see the impasto brushstrokes and even the canvas behind it. What’s weird is that this version seems way darker than any other pictures you may find online. Not sure what’s up with that as it appears they took great care to make the photo