Aside from the top attractions, walking around Rome is like walking around an outside museum - a surprise around every corner.
Check out https://www.walksofitaly.com/
Sometimes you can schedule a tour the day before or even the same day if they have room. Groups are small.
Similar touring guide is https://theromanguy.com/tours/italy
In addition, maybe check out this website:
She is "boots on the ground" - has been living in Rome for about 20 years; is married to a Roman.
Her site gives suggestions about where to go, where to eat.
She gives a lot of updated information about what is going on with restrictions etc.
Naturally, it is always best to check direct websites of any attractions or restaurants for the most current policies and information.
Oh. Remind your son to be extra mindful of keeping anything of great value in pockets or in his backpack if he carries one.
Never put a phone or a bag unsecured on a table or bench where someone can just take off with it.
All the times I've been to Rome as a traveler; did not have any issues. Practicing common sense and personal safety was key.
If he goes into the Vatican museums or the Colosseum or the Borghese, large backpacks will need to be checked. Security had been allowing backpacks and travel bags up to about 14 inches without being checked.