I can't change video format on iPhone XR when I try to use it as MacBook camera

I need to record myself using the main camera (iPhone XR, iOS 16.5.1), but I want to see myself using a MacBook (Air M1, macOS Ventura 13.3.1). I need the format to be 9:16, but I'm unable to change it. You can see more details in the attached video. How can I solve this problem? Are there any alternative solutions?

I apologize if the translation is not accurate. I'm using a translator, so please ask me to clarify if something is not clear.

Video:

https://drive.google.com/file/d/1TSWOdGOziLASQqPGzQOvWmLdrn0b-kbY/view?usp=sharing