I never got all this hype about the leg drive during a bench press. Really. Famous coaches like Louie Simmons and who not are talking about the bench press like it is some sort of science. Let me tell you something - leg drive during a bench press does not do much. I would even say that it may be problematic if you are not very experienced because if you use your legs too much you may get out of posiiton and who wants to get out of position? Leg drive is overrated. Want a prove?
Here's Siamand Rahman bench pressing a ton of weight and he obviously is not able to use leg drive.
There's no need to overthink. Just make sure your legs are firmly connected to the ground and use them to keep yourself stable on the bench. Other than that it's pretty much only upperbody.