If I start enjoying smaller dicks in my porn games, will that make my cock grow, since my fantasy will be "have a normal sized dick"?
Eh, more on the point, size does matter. There is such a thing as too small and also too big. On average, anything above 17cm is bound to be uncomfortable for women. I think the sweet spot is something around 12-16cm (not converting that to drunken thumb measure), so there's a lot of wiggle room. Women might certainly find bigger dicks desirable, but real life size queens, women that can only be satisfied by porn-sized dicks, aren't common.
Also, as
dainsleif noted above, size
isn't everything. For the virgins reading this, sex can be one hell of a workout, especially for the abs and thighs. To give you an idea, get into a pushup position and start thrusting your hips. Then try thrusting as hard as you can. Tell me how long you can keep it. Jackhammering a girl for more than 1 minute straight is a feat.
Now, porn is just fantasy that acts straight on our monkey/lizard brain. I don't know nor fully understand why unrealistic big boobas look so damn enticing, or hips so wide I have trouble hugging look so desirable to me. I understand, on a rational level, that anything like that in real life is either the result of a surgery or something very, very wrong with the person's health. I'm also perfectly aware that you should not even try to "womb fuck" a woman, unless you want to kill her.
But since the rational part of the brain is the most easily overriden, if our monkey brains associate bigger = better, then it's pretty obvious why some people desire bigger boobs, hips and dicks, though most people have a size limit to what turns them on. The rest are into macro