I may be out of line here, but why? Hundreds if not thousands of photos of practically any masterpiece you may want to view on the internet. Unless of course you want to prove you were there. Then a cell phone selfie does the job quite nicely.

I travel fairly extensively and visit museums where ever I go. It has become very prevalent now that the crowds are at the museum only to appreciate art by taking a photo. You cannot really It is becoming virtually impossible to appreciate great art anymore without hoards of people filing past, pausing only momentarily long enough to take a photo. Why bother going to the museum at all if this what you are going to do when you can sit at home and do a virtual tour?

Here is my suggestion, based upon my experience. I shot with a D500 in a number of galleries and houses of worship. The camera is 'pretty darn' good in low light situations. Best to take with you a 'faster' lens and more of a wide angle. Nikon's 18-80 (or 85) or 17-35, would both work exceedingly well. There is VR in the camera - you don't need a tripod as such would also bring the docents to your side in a flash. As well, do not use a flash; that is verboten in an art gallery.
Have a wonderful trip!

Different strokes for different folks...I've been to Italy twice. 1st time I took my Nikon DSLR with a couple of lenses and the second time I took my Nikon A900 P&S. The second time was MUCH more enjoyable. No hassles with equipment. Just one little camera either in my hand or in my windbreaker pocket. Usually moving fairly quickly to keep up with the tour. The A900 offers full manual control if you so desire, but doesn't have RAW. 20 mp, 24-480mm equivalent. It also has a panoramic mode for that "The Last Supper" shot in Milan that you're going to want. There are a plethora of point and shoot or bridge cameras on the market to fill the bill. I was happy with the results. BTW, I never used the flash...anywhere. The last two are examples of photos taken in a museum without a flash or a tripod. We're taking our family to the Dominican Republic in three weeks. I'll be taking my Olympus TG-5 for underwater shots and either my Sony RX10 MK IV or the Nikon A900 (old but reliable). The R6, D500 and X-T4 and tripod will be safely tucked away in the closet. You're going to love Italy, Ray.

Do everyone a favor and get a camera that can shoot silently, rather than slap a mirror and mechanical shutter with every shot.

Get one with excellent in body stabilization, so you can shoot at low shutter speeds and low ISO.

And use lenses with large apertures as well, since you don't need deep DOF for paintings (f/2.8-4 FF equivalent is good).

Learn to do custom white balance, or use a color profiler, to get correct color.

And learn to do keystone correction in post processing.