How to correct my pecs

Hello there,
I want to ask my coach for more exercises to develop my muscles at the level of the sternum, in order to strengthen and develop the upper pecs a little and thus have a drawn line.
And especially to correct the bottom. As you can see on the right in the photo, my left pectoral deviates higher to the left and therefore I still have this asymmetry of volume and strength, very deviated. I want to erase this difference and develop this environment. How should I do for this? What exercises can help with this? Should I gain more weight for the less developed muscle?
Don’t ask me to do one-handed pushups, I can’t. But any other information will be welcome. Also, excuse me if I’m reposting this question in English, because in the French forum I didn’t get an answer. Thank you in advance, because it bothers me a little. I asked my coach to develop my pecs but I do not think I was so precise…

Look up lower pectoral dumbbell exercises, focus on that one side.

Thank you for the advice. I saw that a good exercise would be the inclined bench press. As always, it will take time. I train four days a week but as a 50 years old ectomorph, it was always difficult for me to gain muscles. But I won’t give up, I do like Freeletics very much.

You look great for 50 years old! I would have never guessed your age.

Thank you… sorry for the delay…