I did that few weeks ago after reading a similar comment here on hn. It helped, phone was less interesting; but then monkey brain made it a challenge game to assume, guess & fill colors in screen display images. More brain taxing, I changed it back to regular.
I never thought to do this and already enabled it per your comment. Let’s see how it goes the rest of the weekend.
I genuinely prefer greyscale displays. If I weren't visually impaired and/or so much UX didn't rely on color, I'd turn it off permanently except for art creation.
Color filters under Accessability, for those on iOS.
Same place on Android, incidentally.
I wasn't even aware that's an option.
If nothing else it might make late night usage of the phone much less disruptive to sleep.