Until what time can I stay in the room?
FI-no — stress on the first syllable. 'Fino a' means 'until/up to'.
Ask at check-in to know the check-out time and plan your last day accordingly.
'Fino a che ora' means 'until what time' — 'fino a' (until) + 'che ora' (what time). 'Restare' means to remain or stay. This is the most natural way to ask about check-out time without using the English term 'check-out'.
A che ora è il check-out?
What time is check-out?
The anglicism 'check-out' is universally understood in Italian hotels
È possibile avere un late check-out?
Is it possible to have a late check-out?
Ask this at least a day in advance — availability depends on bookings
Se parto tardi, posso tenere la camera fino al pomeriggio?
If I leave late, can I keep the room until the afternoon?
Some hotels charge half a day's rate for this service
Standard check-out in Italian hotels is noon (mezzogiorno). Late check-out is often possible for a fee or, in lower-occupancy periods, free of charge. Asking politely the evening before yields better results than demanding it at the last minute.