Googled from UK gov website.
Public spaces and travel within Italy
Public spaces and services
From 1 May until at least 15 June the use of FFP2 masks are compulsory in the following cases:
When entering Italy by plane, ferry, train or coach
On public transport within the country, including commercial flights, boats, ferries, interregional trains, buses, subways, cars and taxis with a driver
At indoor public venues such as theatres, concert halls, cinemas, live music clubs and indoor sporting events
When visiting healthcare facilities.