expression
having a place to oneself; having the run of a place
Colloquial expression used when a venue like a restaurant, theater, or park is so empty that it feels like it's been reserved for you.
平日の映画館は貸切状態だった。
The movie theater on a weekday was practically reserved for us.
このカフェ、朝早いと貸切状態で気持ちいいよ。
This café feels like you have the whole place to yourself if you come early in the morning.
貸切 means 'reserved' or 'chartered' and is used when a place is actually booked for private use. 貸切状態 is a figurative extension meaning it feels reserved because it's empty.
Compound of 貸切 (reserved, from 貸す 'to lend' + 切る 'to do completely') and 状態 (state, condition). The phrase literally means 'reserved state' and is used figuratively for empty venues.