Why is my iPad Air 5 treating connected displays as a duplicate screen?

Before purchasing an iPad Air 5 I saw several YouTubers demonstrating that once you connect an external display to an M1 iPad with an attached keyboard/mouse and enable Stage Manager it will treat the display as an extended display instead of a duplicate screen. However, when I try this the external display always duplicates the iPad screen. I am running iOS 16, and I have tried both televisions and monitors as external displays. Why is the external display duplicating the iPad screen?