Will Yip is using the UAD API Vision channel strip to enhance each distorted guitar track in the mix individually.
He employs preamp gain for character and presence, should the track lack these qualities.
He also applies a gentle high-pass filter around 30-40Hz to reduce muddiness, and adds light compression (1-2dB reduction, 4:1 ratio, medium attack, fast release) for consistency.
The main emphasis is on EQ, particularly boosting around 700-800Hz for tone and 7kHz for presence, creating a sound that's musically rich and detailed, avoiding boxiness or harshness.