Yes, you can normally use Roaming which is for free - BUT: If you come across a certail treshold, you'll be charged more! There's a formula: https://www.o2online.de/service/auslandsoptionen/eu-verordnung/
Monthly price / current wholesale price * 2 = your usable GBs
wholesale prices are:
- from 01.01.2025: 1,547 €
- from 01.01.2026: 1,309 €
- from 01.01.2027: 1,19 €
So if you pay 20€/month than in 2025 the calculation is:
20€ / 1,547 * 2 = 25.86 -> if you use more than that, you'll be charged 1,55€/GB! --> which means, if you use 50GB, you'll be charged 25,86 + 37,20 = 63,03!
There are merely two alternatives:
TIM: https://www.tim.it/fisso-e-mobile/estero/dall-italia/tim-tourist
Windtre: https://www.windtre.it/offerte-per-turisti-in-italia-en
--> I visited a shop in Follonica and got a better deal:
150GB = 15€ + 9,99€ activation fee --> next re-up of the limit is only 11€ for 150GB and will work online/through Windtree App
Have a look at a comparison portal: https://esims.io/de/countries/italy?srsltid=AfmBOoqZOIyx7TrIxJxW9xtBRs9oqBq0l3ha9EtBybSJ3YF548mAYGcn They also have coupon codes.
There are a lot eSIM providers around, where you can buy unlimited traffic for 1-n days.
https://yesim.app/de/country/italy/7days-unlimited-esim-data-plan/
unlimited 7days = 22€
coupon code esims24
--> I tested Yesim and they sadly seem to have limited the max speed to 10MBit/s - thus rendering the eSIM option useless for me (not enough speed and much to expensive -> simply visit a store!)