I use iPhone in grayscale mode most of the time. There are, however, apps for which I want the grayscale to be disabled, like:
This way is great for enabling/disabling the grayscale mode on demand. Thanks to the Accessibility Shortcut I can do it by pressing the Side Button 3 times.
This article describes how to setup this Shortcut.
This feature requires iOS 16 AFAIK.
For the some apps, like the aforementioned Camera, I've set a Personal Automation in Shortcuts that disables grayscale when I open them and reverts back to greyscale once I close them.
I also have another Personal Automation that resets to grayscale each morning.
Here's an example on how to make a Personal Automation for Camera:
Due to iOS limitations you have to set the Personal Automation for each app separately.