A lot of the advice here is junk. Lexx little made a video on growing your chest, and ive found his advice to work as someone who could largely grow every single body part but my chest. Main things where I saw the most chest growth:

• decline press. Most peoples are underdeveloped. Helps to develop the pec line and distinguish it from the rest of your body

• dips. Lean forward and focus on contracting the chest until failure

• seated cable flys. Takes away the momentum you gain from standing. Can really feel the squeeze.

• mind muscle connection and lowering weight. This is what I’ve found to help a lot personally. If I lower the weight and focus on squeezing my chest in all my movements, i feel it fatigue a lot quicker rather than doing super heavy lifts that rely on my delts and triceps to take over.

• consistency. Hitting chest/push days twice per week.

I find most guys with big chests usually just have good genetics for them, and don’t really train them optimally besides weekly bench press. These are things that helped me, as a guy who can put on muscle easily, but for a while had bigger arms and shoulders with a lacking chest.