Off course there are variations both in 'width' and in 'depth' and there can be a big difference in lubrication, from just wet to flooding.
Lubrication can also vary in the same woman, dependant on the time of the month, usually increasing towards her ovulation time (she also gets most horny then).
If a woman has done kegal exercises she can vary the tightness but losses the ability when she nears orgasm. I had a partner who was the 'perfect fit' until those last few moments when she turned into a 'bucket'.
In 48 of them I have been with women varying from very tight, even fully 'ready' (but not impenetrable with care and consideration) to ones who could (I think) have taken my fist (some do even take fists).
I've also been with women who despite being full aroused and 'ready' have (initially) had problems with my length (8.5") in missionary position, to ones who could take it in one push in cowgirl. I've had 2 partners who could never fully 'take it' in cowgirl and I've had others who wanted it that way straight away.
These extremes do rather bring into doubt the saying "penis size doesn't matter" because to them the size of a cock probably can.
I personally know that the 'larger' women have definitely preferred and wanted a larger cock, either/or both in girth and length.
You will read over and over that women like to feel 'filled', some even 'stretched', so vagina/cock match, as well as performance can be important.
Both partners want to get the best sensations - so pencils in buckets, or bulls in virgins, are no good for either one.