There are no “buttons” on an iPhone; this is by design.

I tested several apps on my iPhone (13 mini) and none require a swipe from the left edge rightward to “go back.”  This can be achieved with a rightward swipe from the center of the screen.  

 On Apple products, it’s more about the gesture than the actual location where you take the action. [Other than some very specific gestures][1] like opening Control Center, unlocking the phone, and seeing notifications, things like navigation are recognized anywhere on the screen. 


  [1]: https://support.apple.com/en-us/HT208204