I`m pretty sure such topic is extremely complex. Take paper and pen and try to draw how big is your dick. I’m pretty sure result would be quite off after measuring and we actually see our dicks everyday. There is no way to remember how big was someone exactly even after short time, it becomes some vague “like this” and after long time its completely distorted. So even when women don’t lie, impression of size would differ much. If we wanna sort out it more, it`s better to start from the reason why person thinks something is really big.
When I was teen, I thought my dick is quite small or average at best. Reason for that is because any other dick I saw or heard of was from porno or wrong measuring with a bit exaggeration. Even when girls said I have big one, I didn’t trust them much and thought about that more like flattering. You can clearly see how opinion is formed in comparison and how hard to change that. I visually don’t see it bigger, when I grip its easy to form O-shape with fingers and even some extra space is left. That way I don’t have any indicators my dick is big. In reality I have quite big hands, for me thump-index distance is 8in and even when I form ring, its huge ring.
For woman to think its huge, that has to have stunning indicators. Its like surprise effect. Woman had 5-10 small partners then appeared someone with decent size and she thought he is huge. Now that word is associated with him and even if we pop up many similar or slightly bigger, it becomes only common. If you ask what was her biggest she might remember that ex, because she still has impression he is huge. To overcome that we need absurdly big size and you can see it actually doesn’t have anything to do about actual size, but just impression she had when saw it. For sure there are many such indicators. It might be length, thickness, body size, her feelings and so on. Make her squeeze, she feels tightness and thinks its huge. Nothing about size, just her feelings, some woman can squeeze even pencil.