Most of it is just in focus modes settings: alerts, notifications and things like that.

For greyscale you use shortcuts. There’s an automation tab, you set up on a focus mode being enabled then “set color filters on” and then the opposite for that focus mode being disabled.

For me I use the accessibility shortcut, three presses of the side button pops up a menu so I can select color filters (grey scale) and reduce white point (80% is my default). I enable both when I am reading. It's really helped eye strain when I'm reading.