High-rep finisher sets have their place in bodybuilding. And they're not just for building mental toughness. They also create metabolic stress (the pump) which is one of the primary drivers of muscle growth.
Just finish off your workout with one 50-rep set. Use short rest-pauses if needed toward the end: do as many reps as possible, then take 10 deep breaths and go again. Repeat until all 50 reps are completed.
Or you can break this into two 25-rep sets with only 30 seconds between the two sets, but the goal is to get all 50 in one shot eventually.
Here's Chelsie Lysenchuk using goblet squats as a leg day finisher:
Find a dumbbell that's a quarter of your bodyweight. So if you weigh 200 pounds, that'd be a 50-pound dumbbell or kettlebell.
Now do goblet squats for 50 reps. Remember, this can be a "broken" set. You can stand and catch your breath as needed, but you can't put the dumbbell down or sit.
If you're truly sadistic, do these in pump/piston rep style where you don't lock out. Those will hurt a lot and increase the metabolites a hell of a lot faster than doing full-range reps with a lot of breaks during the set.