Can I sit in first class if my ticket is standard?
stan-DARD — used as-is from English. pri-MA KLAS-se — stress on first syllable of each word.
Ask the conductor when you are considering upgrading or when first class appears empty and you want to know if you can use it.
Posso sedermi (can I sit) — reflexive verb sedersi (to sit). In prima classe (in first class). Se il mio biglietto è standard (if my ticket is standard) — standard is used directly as an English borrowing in Italian railway contexts.
La prima classe è vuota, posso spostarmi?
First class is empty, can I move?
Even if empty, you need a valid first class ticket or upgrade
Quanto costa fare l'upgrade qui sul treno?
How much does it cost to upgrade here on the train?
On-board upgrade from the conductor — usually more expensive than pre-booking
La prima classe ha posti prenotati tutti?
Are all the first class seats reserved?
Checking whether any first class seats are genuinely available
Trenitalia's first class (Prima) on Frecciarossa offers wider seats, more legroom, a complimentary drink service, and quieter carriages — the upgrade is worth considering on journeys over two hours.