How do I create a floating UISheetPresentationController?

I currently have the following screen, implemented through a UISheetPresentationController:

I would prefer that the screen look like this (i.e. I'd like to preserve the UISheetPresentationController but make it not pinned to sides and bottom)

I tried to use the sourceView property to do this, and followed all instructions in documentation but nothing worked. Is this possible without creating my own custom view that replicates a bottom sheet?