When it comes to training the chest, there is one exercise that I have been performing for over 30 years now: dips. Between the ages of 12 and 15 I competed as a gymnast. The training was intense. My coaches used to torture my teammates and I with 45 minutes of strengthening and conditioning at the end of each practice by utilizing mostly body callisthenic exercises. One of those exercises that they employed every single time was chest dips. As a 12 year old kid, I was able to witness first hand just how powerful and effective tis exercise was at training the pec muscles. That is why I have been performing them ever since. When it comes to building powerful pecs, this exercise should always be in your arsenal. To perform the exercise:

For this exercise you will need access to parallel bars. To get yourself into the starting position, hold your body at arm’s length (arms locked) above the bars.
While breathing in, lower yourself slowly with your torso leaning forward around 30 degrees or so and your elbows flared out slightly until you feel a slight stretch in the chest.
Once you feel the stretch, use your chest to bring your body back to the starting position as you breathe out. Tip: Remember to squeeze the chest at the top of the movement for a second.
Repeat the movement for the prescribed amount of repetitions.

If you are new at this exercise and do not have the strength to perform it, use a dip assist machine if available. These machines use weight to help you push your bodyweight.

Otherwise, a spotter holding your legs can helpful.

More advanced lifters can add weight to the exercise by using a weight belt that allows the addition of weighted plates.
I find that performing this exercise near the end of our chest workout can be helpful to finally push your pec muscles to their brutal limit. I can still hear my coaches screaming “We Love Pain!” while they made us do these. At the time I wanted to strangle them. But looking back, I realize they were giving me one of the best chest building exercises that ever existed.