Squatting and targeting the quads is highly linked to biomechanics.
The guy on the left will say that the squat is very good for quads (torso more upright) while his friend on the right will recruit way more posterior chain.
So, if you are the guy you should maybe add a wedge under your feet to allow the knees to go further.
Last one, front squat position, more quad dominant than the back squat (easy to see why…). Maybe you’ll use less weight on your bar but it will be use more by your quads than your glutes, hamstrings, etc.
There is a lot of information in the Delavier and Gundill’s books about bio mechanics.