Unlock the knees.

As you bend your knees to descend, push them outward to ensure they track over your toes. They should follow this same path on the way up so that the bar stays balanced over your mid-foot throughout the lift.
Knees over toes.
SQUEEZING YOUR GLUTES
SQUEEZING YOUR GLUTES
THE CLOTHESPIN ANALOGY
THE CLOTHESPIN ANALOGY
MAINTAIN FORWARD KNEE POSITION
MAINTAIN FORWARD KNEE POSITION
Juggernaut
As long as you break at your hips and knees at the same time or even your hips first if the knees cross over the toes later that's absolutely fine.
Renaissance Periodization
Your knees should generally point in the same direction as your toes. They shouldn't cave in or be forced out excessively...
Jeff Nippard
Keep your knees inline with your feet... Your knees should end above your toes at the bottom of your Squat. They’ll be more forward if you have long thighs than if you have short thighs (or long feet). But your knees should end inline with your feet and almost directly above your toes... Knees out creates space for your belly and makes it easier to break parallel. It engages your groin muscles which increases your Squat. And it prevents twisting of your knee joints. Don’t let your knees cave in during heavy Squats or you risk injuring your knees.
StrongLifts
If I push my knees out slightly, this gets my femurs out of the way to create space and I can keep a little bit more upright back angle.
Super Training
External rotation is the rotation of the leg AWAY from the midline of the body... Ultimately, the goal is to turn your femurs outward to open the hip capsule and allow the hip to bear the load on our back. This also allows all the bony landmarks, where tendons are attached, to rotate out of the way. Stand up and put your left foot out with your heel on the ground and toe up. Now rotate your foot outward away from your body. Feel that? That’s your glute firing. Now stand in your squat position. Contract the glutes and rotate the leg out towards the pinky toe WITHOUT letting your foot slide across the floor.
As you’re standing up, don’t forget to keep pushing your knees out as well. If your knees are caving in, your shifting the stress to your quadriceps and adductors, versus your glutes and lateral hamstrings.
Robertson Training Systems
Push your knees out in the bottom of your squat! If you're in the bottom of a squat and you have no other place to go, the reason why is because your body is in the way... That's why you don't see a pregnant lady just flop on a couch; she starts pushing her knees out to allow room for her belly... You need to push your knees out to create a little bit more space and still be able to maintain position then come out of the hole.
A lot of people... when their knees go in, they use the cue to drive the knees wide... Their foot comes into a good arch; so that's a really great cue. However, if you drive your knees real far wide... you just become unstable. So that whole 'drive the knees wide' only works to a point because if you drive the knees too far wide then you just become unstable in other positions... on the outside of the feet.
Barbell Shrugged
Balanced over mid-foot
BARBELL OVER MIDFOOT
BARBELL OVER MIDFOOT
whiteboard_daily
HIP SHIFT
HIP SHIFT
As you descend and stand up you should remain balanced (or heavy) throughout your entire foot. Feeling heavy on your heels or heavy on your toes would indicate you are not balanced...
Alan Thrall
Your most efficient squat path is going to be a straight bar path... and what what we want to do is try to get it as close to straight as we can... directly over our mid foot - that's our center of balance and gravity.
Super Training
I'm really pushing my knees forward over my toes... that's not bad for knees unless you're letting your weight shift forward onto your toes [so] no matter what you want to make sure you keep your weight balanced over your mid foot... and that way you're gonna make sure that you're not just engaging your quads, you're gonna be engaging all the muscles in your lower body.