I always made sure to not only do a lot Of reverse grip back work (because I always felt a better pull in my lower lats) but to ensure my rowing movements were performed low, to my waist. This really helped me keep my arms out of the movement, but also feel a better contraction on my low/mid inner back and Lat attachments. On occasion I made use of a smith machine so I didn’t have to worry about balancing the bar, and would position my torso very far forward over it.
For lower chest, dips are king, but if you don’t get enough out of them (I always felt uncomfortable doing chest dips), I used to like 3 Olympic plates under one end of a flat bench to create a slight decline for dumbbell presses. This was one of those magic exercises for me when I stumbled upon it. Always having relatively weak pecs, and with flat work always hitting my delts more, this was a mainstay in bringing up my mid/lower chest.