The lower edge of the pectoral muscle is the inferior oblique muscle, which always has fat, which proves that you haven't practiced the inferior oblique muscle much. How many men have been lying on their backs for years, bleeding and sweating, but they have developed a "splayed chest" in the middle of the outer drum, and how many men have developed a girlish "round" chest, which makes them afraid to wear tights.
It is suggested to practice chest muscles: barbell bench press, first flat plate, then inclined plate, then inclined plate; Then dumbbell bench press, first flat plate, then inclined plate, then inclined plate; After that, the chest is crossed and the bird practices the inner chest muscles. The weight only increases, with eight to twelve in each group and five in each movement. Stick to it for a month or two.
I hope you can have a perfect chest shape as soon as possible.