In a WhatsApp videochat on my iPhone (XR, iOS 12.4), how can I switch between front and back cameras? When videochatting with WhatsApp (v2.19) on an iPhone (XR, iOS 12.4), the front camera is used because when you look at the screen you want the other person to be able to see your face. But using the back camera would allow you to show the other person your surroundings while viewing on the screen exactly what they are seeing, in other words using the screen as a viewfinder.

How can I switch between using the front and back cameras during such a videochat?
There's a camera flip button in the bottom, beside the end call button. See the snapshot in the video in FAQ https://faq.whatsapp.com/en/iphone/26000028/?category=5245237