Well, I think that anywhere you go, you will risk paying a lot more for a touristy meal that is of a lower quality, compared to the local, small, less known restaurants
It's only normal, touristy places are always packed, especially during peak season (mainly during August), so they have to cook a lot of food in a really short time, and yes, their prices are higher than usual.
However, regardless of where you will go, you can always take a walk along the less tourist areas.
Do visit the main landmarks! It's an absolute must to see the main tourist attractions if you're in Italy, but if you want to eat well, I suggest you walk away from the main streets and try to find smaller, less crowded places to eat.
For instance, if you have the possibility, try eating outside of town. There are many trattorias (or osterias, both are food establishments) you can find in the small towns or villages, hey offer great food and the prices are always lower compared to restaurants. You can find trattorias and osterias in the city as well, you'd just have to walk / drive around a bit to find one that isn't located right in the heart of the city.