The faders of the channels and groups of a mixing console control the levels of the signals to the multitrack recorder and to the mix.
The fader itself cannot boost the signal level, it can only reduce it. There is usually an amplifier before the fader with a fixed 10 dB gain.
At its zero position, the fader itself lowers the signal level by 10 dB giving a resultant gain of 0 dB.
The fader has no influence over whether an individual signal is distorted or not. If the signal in a particular channel is distorted, the gain setting is too high. Lowering the fader will simply lower the level of the distortion.
It is important to remember that if a channel is routed to the mix, then it adds noise to the mix - even if the fader is pulled all the way down.