We have a house in Italy so a fair amount of experience in sniffing out good restaurants.

I've found the best, most reliable resource is Michelin - https://guide.michelin.com/it/it
The guide is more than */**/*** restaurants. They list quality restaurants that are not awarded stars. Also, they have a category "Bib Gourmand" which are quality meals at good prices.

A good app is "The Fork" - you can use it to book many restaurants which can be easier than calling if you're not comfortable booking reservations (prenotazioni) in Italian.

Steer clear of TA as it's notoriously filled with fake reviews/ratings.

Make reservations as early as you can as good restaurants in popular locations book quickly (and many restaurants do 1 seating for a meal as they won't rush you off a table). Two keys to eating well in Italy - 1) eat when Italians do, what you get for food outside "normal" meal hours is a waste of a culinary bullet and 2) make a reservation as the good places book out early.