For Steam
You can hit ~ to bring up the console in-game and use m_sensitivity 2.026499 to set it precisely for now. Obviously use your value instead of mine.
edit: I don't know why I wasn't working before, but adding "+m_sensitivity 2.026499" with the quotes to the Steam launch options seems to work for me now.
Name: Control Website: https://www.epicgames.com/store/en-US/product/control/home Status: Release Release date: August 27, 2019 Availability: Purchase
The game has a slider from 0 to 100. I can't seem to find a config file, at least one that is in plain-text.
For what it's worth, 10/100 seems to be just a tad too slow to match my 1.56 800 dpi 1920x1080 106.56 fov CSGO setting.
10/100 gives me 15cm/180
9/10 gives me 17 cm/180 and I'm aiming for 16cm/180 lol.