Is it worth getting an eSIM for Italy?

Yes, an eSIM is useful if your plan doesn't include data in Italy or if you're traveling from the United States; if you have a French plan with enough data for EU roaming, you can generally do without it. Still, check the data limit usable abroad: it may be lower than that of your plan in France. A travel eSIM often costs a few euros to around twenty euros for a short stay, depending on the amount of data and the duration.

In Maremma, it will mainly be useful for maps, schedules and bookings when you don't have Wi-Fi. But it doesn't guarantee network coverage everywhere: in isolated villages, in the hills or on certain stretches of road, reception can weaken, and this depends on the operator used by the eSIM. For big cities and usual routes, it's generally less of a concern. Before buying, check that your phone is eSIM-compatible and unlocked; some offers are for Internet only, without regular calls or SMS. You can then keep your usual SIM to receive calls, by disabling its mobile data to avoid roaming charges. Install the eSIM before departure, then activate it on arrival.