Flex your chest before and after training it…flex and squeeze for 30-45 seconds and you will start to get a pump in your chest and will be able to engage it more easily.
Looks stupid, but definitely works
I’ve made flys as my main chest exercise, and seeing better progress.
Also, when benching (as 2nd exercise), I focus on flexing the chest, pressing my arms inwards, instead of the powerlifting “ripping the bar apart”. let triceps get their own sets…