273,
Now you are introducing red herrings. Your original story, which was wrong, was that a bigger piston exerted more force because of it's greater area.
I do not know how many examples are needed until the message sinks in. So I will try some humour....
There is a lump of dog s**t on your patio. You get the garden hose to get rid of it. You adjust the hose nozzle for a concentrated stream...& blast away the mess. Had you used a fan pattern with the hose, it would not have removed the s**t. The pressure was the same in each case, but spread over a wider area with the fan pattern, & therefore less force per unit of area.