Yes, you have the option to set the Cover screen timeout of the Galaxy Z flip5 (in Settings > Cover screen > Cover screen timeout). But the longest duration you can set is 30 seconds.

There's a way to make it slightly longer. Yes, only slightly.

First, you'll need to install the CoverScreenOS app. This is an app that allows more customization on the Galaxy Z Flip phone cover screen.

Once you've installed the app and allowed all the necessary permissions, go to Settings and then Screen timeout duration.

Something longer than 30 seconds would be either 45 seconds or 60 seconds.

Video tutorial: