You can adjust the sensitivity to your liking depending on your windows sensitivity/settings and preferences.
Your input.ini file is located in this directory: "C:\Users\*UserName*\AppData\Local\b1\Saved\Config\Windows".
Place the below text in your input.ini file and set it to Read Only.
[/script/engine.inputsettings]
AxisConfig=(AxisKeyName=“MouseX”,AxisProperties=(DeadZone=0.000000,Sensitivity=1.200000,Exponent=1.000000,bInvert=False))
AxisConfig=(AxisKeyName=“MouseY”,AxisProperties=(DeadZone=0.000000,Sensitivity=2.500000,Exponent=1.000000,bInvert=False))
bEnableMouseSmoothing=False
bDisableMouseAcceleration=True
bViewAccelerationEnabled=False
Author : Ile