iPhone Shortcuts - A QUICK SHORTCUT TO TAKE VIDEO
On iPhone 11 and later models, you can record videos without even switching out of the default photo mode.

To capture a quick video in the Camera app, just press and hold the shutter button, then release it to stop recording.

To keep recording video without having to hold the button, slide the shutter button to the far right. The shutter will stretch with your finger as you do it, and a target padlock icon will pop up. When placed on the padlock, the shutter button will remain located there for as long as you shoot video. You can also tap the shutter to take a still photo during the recording. When you're ready to stop shooting video, tap the record button below the viewfinder.