You are lieing. There is no cock who can not enter any pussy or there is no pussy who can not take any biggest cock. There is question of hymen only and which is vert easy to break. Inside hymen and outside the hymen any pussy is very big and can take a horse cock too.
Since a vagina can pass a newborn infant theoretically it can accept any size penis, but in practice penises and vaginas are not universally adapted. The psychological factor is big, since women who are scared or apprehensive will clench down, but if you are much bigger than average there will be those vaginas you just are not going to have a pleasant time with and SHE is not going to have a pleasant time with it either.
I'm right at 8" long and about 1 1/8" right behind the corona at the widest part and I have never had a woman I
could not enter but I was clearly at the limit with a couple. There are guys a lot fatter than me and several I have talked to have run into girls where it was just flat out no go.
Usually the problem is with younger and less experienced women, but some are just tight in there. Years ago, I had a nineteen year old college girl notice me and she made it clear she was interested. We went out, we got a room, and it turned out she had only been with two other guys who were much smaller. She got nervous and it took a tremendous amount of foreplay and massaging before I could get her loose enough I could enter her with what I thought was a comfortable amount of force. Afterward she clearly was sore and I felt really bad. I don't want to hurt anyone.
I mostly only date women over 45 or so and most of them are quite comfortable with my size. Time, use, and a baby or two will loosen it up to where the pecker that was too big when she was younger is now perfect or even a little smallish if she had her ideal size. But some of them are tight even at 50.