I.e. color correction can be set up with grayscale which allegedly will help reduce screentime[1]. Hence requeting a tile to turn color correction (and thus grayscale) on and off.
There are already two shortcuts for toggling colour correction… might one work for you?
Pulldown system menu: Find the CC button/tile thingy and arrange so that it is in the first 4 options (or the first 8 if you don’t need as frequently).
Instructions:
Drag down the menu from top (all the way, so drag down a 2nd time)
press the pencil ‘edit’ button
find ‘Colour Correction’ and move it up to the top with a press&hold then drag.
click the back arrow then close the drop down.
Toggle CC with a quick, pull down and click.
Other option, Add the CC toggle shortcut. (Which @AnotherElk suggested)
Find CC in settings (or simply long press on the pull down button described above)