On iOS 14 "Capture outside Frame" has been replaced by "View outside frame": See this page in the iPhone User Guide: Change advanced camera settings on iPhone - Apple Support (the last paragraph):
Turn View Outside the Frame off and on
On iPhone 11 models and iPhone 12 models, the camera preview displays content outside the frame to show you what can be captured by using another lens in the camera system with a wider field of view. To turn off this display, go to Settings > Camera, then turn off View Outside the Frame.
This "Capture outside Frame" feature has been a bit awkward, as it had to be turned off, if we wanted to use the advanced fusion features, like Nightmare or Deep Fusion. It has been to much trouble to have to remember, if "Capture outside Frame" is on or off and manage this setting, every time we wanted to use the advanced scene capture modes. For me, the new way is better. I am simply taking all photos zoomed out a bit to be able to crop and compose the scene later.