The Downtime feature on iOS is like a Do Not Disturb feature that goes both ways – you won’t be notified about notifications from low priority apps, but you won’t be able to use them either. Though with the current implementation, the time window you set applies to the entire week.

— Sam Spencer (@Mr_SamSpencer) January 26, 2019 With the implementation in iOS 12.2 beta, you can set your time window for individual days of the week. This is useful for those who want to, for example, spend more time at night on their phone during the weekends. That said, it’s unclear if you can set different permissions for apps on different days. To get to the feature, you’ll have to go to Settings, followed by Screen Time, and then Downtime. Since this is a beta version of iOS 12.2, it’s likely that the final version may see more changes to the feature. (Source: 9to5Mac)