https://www.italiarail.com/travelling-children In most cases, children under 4 travel for free. Children up to 14 may
also travel free or at heavily discounted fares when riding on
Frecciarossa, Frecciabianca and Frecciargento trains, as well as Thello
trains. For all other trains, the maximum Child age is 11. Seat,
couchette and other reservations must be made even for a child traveling
for free and still requires a reservation fee.
In most cases, children under 4 travel for free. Children up to 14 may
also travel free or at heavily discounted fares when riding on
Frecciarossa, Frecciabianca and Frecciargento trains, as well as Thello
trains. For all other trains, the maximum Child age is 11. Seat,
couchette and other reservations must be made even for a child traveling
for free and still requires a reservation fee.