On iPads with M1 chips with iPadOS 16 Beta 3 installed, the Stage Manager feature can now be used to display and run iPhone-specific apps as a small window.

iPhone-only app can be used on iPad

Some iOS apps have been released for the iPhone but not for the iPad. MacRumors, the US media, reports that the multitasking provided by the stage manager function of
 
iPadOS 16 has made it possible to display and use these apps as individual windows on the iPad screen. For example, Instagram doesn’t offer an iPad app, but an M1 iPad with iPadOS 16 Beta 3 installed can be used almost like an iPad app with the Stage Manager feature.
 

Stage manager function is available only on M1 iPad

The stage manager feature introduced in iPad OS 16 is only available on the iPad Air with the M1 chip and the 11-inch and 12.9-inch iPad Pro with the M1 chip.
 
 
Source: MacRumors