Most workouts for lower chest that you find online focus too much on high-rep, pump-style training and recommend doing too many isolation exercises for the lower pecs.
This is a mistake.
If you want to maximize lower-pec development, you need to emphasize compound weightlifting that trains your entire chest (and may emphasize your lower pecs) and allows you to lift heavy weights safely and get stronger over time.
With that in mind, here’s what I recommend:
Bench Press: 3 sets of 4-to-6 reps with 2-to-3 min rest
Dip: 3 sets of 4-to-6 reps with 2-to-3 min rest
Dumbbell Pullover: 3 sets of 6-to-8 reps with 2-to-3 min rest
High-to-Low Cable Fly: 3 sets of 8-to-10 reps with 2-to-3 min rest
This is a mistake.
If you want to maximize lower-pec development, you need to emphasize compound weightlifting that trains your entire chest (and may emphasize your lower pecs) and allows you to lift heavy weights safely and get stronger over time.
With that in mind, here’s what I recommend:
Bench Press: 3 sets of 4-to-6 reps with 2-to-3 min rest
Dip: 3 sets of 4-to-6 reps with 2-to-3 min rest
Dumbbell Pullover: 3 sets of 6-to-8 reps with 2-to-3 min rest
High-to-Low Cable Fly: 3 sets of 8-to-10 reps with 2-to-3 min rest