Dig your feet in.

To balance your weight evenly through your heel. big toe and little toe, think of trying to sink your feet into a sandy beach. Dig the heels and balls of your feet in, then try to grip the sand with your toes while you twist your heels down and together.
Heel + big toe + little toe
EVENLY DISTRIBUTED
EVENLY DISTRIBUTED
You want to make sure you have three solid points of contact with the ground – your big toe, your pinky toe, and your heel – with your weight evenly distributed across all three points.
Stronger By Science
ROOTING
ROOTING
Kabuki Strength
Focus on maintaining 3 even points on contact in your feet throughout the lift, weight should be even through the big toe, little toe and heel. Do not focus on excessively sitting back onto your heels if you are a raw lifter, this is not advantageous because you don’t have a suit to sit back into.
If you have a flat foot, we will try and grab the floor with the pads of our toes WITHOUT curling them and create a higher arch. If your arches are already “high,” we need to grab the floor with the pads of our toes by pushing them down and out to flatten that arch. This gives us the most amount of surface area and stability within our foot, which is the front line of our force production. If this surface is not evenly grounded, the force will not efficiently be transferred up to our legs to our hips.
While curling the toes may be a great way to strengthen the small muscles of the foot, pressing the big toe down and back is the most optimal way for most to anchor the foot to the ground and create an active arch within the foot. This action called rooting allows you to generate sufficient tension in the foot which will transfer throughout the rest of the body.
Squat University
Shift the weight back towards the midfoot, or even slightly towards the heel.
Robertson Training Systems
You should have three points of contact: underneath your big toe near the ball of your foot, the outside edge of your foot, and then the heel of your foot. That's three points of contact.
If we look at your foot, we've got three different parts: the base of your heel, the base of your first toe, and the base of your fifth toe. When you squat, all three of those need to be an equal contact with the ground. That's called a tripod foot... If all three of these points are on the ground equally, you're gonna be able to produce a lot of power.
Barbell Shrugged
Grip + Twist
THE SCREW ANALOGY
THE SCREW ANALOGY
Your whole foot has to stay on the floor. So if you're trying to cue turning out and it's not working and you're still coming up forward do something else. Think spreading the floor apart, driving the heels down, [or else] you're going to start to go down and your mind's going start thinking 'I'm falling forward' then you're going to miss it out of the hole.
“Screw your feet into the floor.” With your feet firmly planted, attempt to externally rotate your hips, like you’re trying to point your heels toward each other, and your toes toward opposite walls. You may feel the outside of your foot pressing firmly against the wall of your shoe.
Stronger By Science
What I'm actually doing with my feet is taking my toes and I'm spreading them out... I'm trying to grip the floor with my feet and then I'm trying to crank it outward... like I have an Eagle Claw or Talon... which leads up to setting my knees, stacking my ankles... give me a good strong base for me to start descending on.
FEET ARE TALONS
FEET ARE TALONS
whiteboard_daily
Grab the floor kind of like a cheetah grabbing the ground or you can try to twist your foot out or you can push your foot out it's all gonna do the same thing, which is trying to keep the foot flat on the floor
THE TOWEL SPREAD ANALOGY
THE TOWEL SPREAD ANALOGY
“Spread the floor.” Imagine a fault line opened up between your feet, and you’re trying to drive your feet apart to rip the crust of the earth in half. This tends to be the most effective for wider stance squatters who point their toes out farther.
Stronger By Science