1 – Use Accommodating Resistance, Like Bands
The resistance curve of the bench press makes it hardest at the bottom and easiest at the top. Your ability to produce force is opposite to this. You're weakest at the bottom and strongest at the top. As a result, the bench press doesn't cause high levels of tension in the pecs across the entire range of motion.
This limits its effectiveness as a chest builder. Mechanical tension is a key element of hypertrophy. Exercises which fully challenge a muscle across their entire contractile range are more efficient muscle builders. Using accommodating resistance (bands or chains) can address this issue and help to match up the exercise's resistance profile with your strength profile.
2 – Squeeze Your Hands Towards Each Other at the Top
Even with the addition of accommodating resistance, the very top of the lift presents an opportunity for your chest to become relatively unloaded and take a brief "rest." As you finish the lift and your arm is fully extended, the joints of the wrist, elbow, and shoulder are stacked on top of each other. Because of this, little tension is going through the chest as you lockout.
By using the coaching cue of "squeezing" your hands towards each other you can help to create tension through the chest. While your hands don't actually move across the bar, the intention of squeezing inwards creates friction. Friction is the force that opposes sliding motion. In this case, it creates a new line of force acting on the muscle and helps to create a sustained challenge throughout the entire range of the lift.
With the combination of accommodating resistance and squeezing your hands towards each other near lockout, you fight gravity hard throughout the whole lift, and when you become mechanically advantaged you use friction to keep tension where you want it. This creates high levels of mechanical tension across the entire range. More tension over a longer ROM equals more muscle.