You set it in the config file to whatever got calculated. In my example above it says under COD:
Multiplier 1: mouse_ads_yaw_ads_multiplier="0.47249"
I looked at your other posts and found your settings: Overwatch 13.01, 49.05% scope, 1200 dpi. If you wanted to try it the same way I did, first you get your COD hipfire sensitivity using cm/360 (called 360 distance in calculator):
So your hipfire sens for Black Ops 4 is "12.99880".
Now let's check ADS sensitivity:
So set your mouse_sensitivity="12.99880" and your mouse_ads_yaw_ads_multiplier="1.29451" in CORRECT COD config.ini, change ADS mode in game options to Legacy, and you should be all done. However I can't promise it will feel any good, your sensitivity is like 4 times faster than mine to begin with, unless you have no desk space I would consider trying like half of it for a while to see how it feels. Good luck either way!