In watching 4K movies, yes.
I go back and forth on the sharpness setting depending on the TV panel as well with some games because some are more stylized than others and also because of differing gameplay priorities; like say with a multiplayer FPS (even with the few games that allow the player to turn off distractions like motion blur) in which the TTK is such that speed of recognizing and target acquisition of an opposing player is by far the biggest determining factor in your K/D.
However, this dynamic is far more difficult and pronounced in some FPS than others, an example of which is Battlefield where the style is far more naturalistic in using a palette of earth tones in the environment and uniform of the players versus an extremely stylized shooter like Fortnite that uses a very bright and contrasting color palette where the players stand out against the environment/background much more.
With my 4K LG OLED, I am able to stick to the rule of thumb of using 0 sharpness as well as turning off almost all related extra post processing elements like super resolution (think that's what LG calls it) far more often but, on the other hand, in my occasional use of the X with my mid tier Samsung LCD 4K TV which is "handicapped" more vs OLED , as it's LCD relies on local dimming and has a less ideal contrast ratio etc etc, I find I have to increase sharpness more often, somewhere between 10-20.
... So, IMHO, it depends.
I know this isn't the cut and dry answer you might have wanted but I hope it does somewhat give you some insight in optimizing for your specific scenario with all it's many unknowns and variables. Just take your time with it, don't juggle changing multiple other settings at the same time, and, after prioritizing which setting's optimization in order of importance to your personal enjoyment , make changes to only one setting at a time and only in small increments.
Don't do as I did and just dive in, changing everything at once, dialing in numerous mayor changes to such a degree that by some time into getting the console, I had utterly confused myself as to what did what anymore, finally, having to just do several default resets, starting from scratch.
It was only fun the first couple hours spent in doing so but got old quick and instilled a self doubt that I still can't shake the feeling of, rather than just enjoying the damn thing, and finding myself thinking that "x" or "y" isn't as good as if could be lol