How to set PreviewProvider to landscape?

I am developing a SwiftUI iPad app and I like to see how the interface looks when the device is held in landscape mode.

I am using the latest Version 12.0 beta (12A6159). However there seems to be no setting to switch between landscape and portrait for the SwiftUI PreviewProvider.

Is this not implemented yet?
How to set PreviewProvider to landscape?
 
 
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