High Bar Feet-Forward Smith Squat, 1.5 Method
If your legs don't grow with this, the only explanation is that you never got vaxxed for Polio. When you do this quad-building exercise, in the back of your mind you're going to want to save some in the tank here. Don't.
We're going to be using the one-and-a-half reps method here. That is, you go down, come half-way up, go back down, then come all the way back up. That's 1 rep.
For these, set your feet out in front of you so when you hit bottom your shins are vertical or very close to vertical. This position is practically identical to the position you're in when you do a lunge.
Do 10 reps this way. (Which actually turns out to be twenty total reps in reality.) Pour everything into it and leave nothing on the table. You should have visions of Abraham Lincoln cursing at you in Kiswahili about how you neglected your stabilizers as you lie on the floor. If you need to rest for 10 minutes or so before moving on to your next exercise for the day, that's perfectly okay.