When you find a girl attractive - do you only look at one thing ??
Just the eyes ?
Just the hair ?
Just the voice ?
Just the tits ?
Just the pussy ?
My response is by complete package I'm sure

My experience is cock size is the same thing with girls
Do cocks matter to them ?? Yes
Is it simply size ?? No from what they have told me

They do love a "nice cock" or even a "beautiful cock" as some refer
But they (from what they have told me) respond to more than size !!

Like
- does it look nice (some prefer circumsized)
- clean look (most i would say prefer pubes trimmed short or shaved)
- shape ..... big head or cone shape / curved or straight
- size .....long or short / thin or fat
- hardness - they love rock hard because it feels better inside and mentally it stimulates them too because it is evidence they really turn you on !!

But ... Guess what ... they have different views about these things - just like we do about body shape / boobs / hair etc
But ... I can tell you they do care about cock .. but way more sophisticated than just "size"

If I had to say .. I would say in my experience the girls consensus is (so not every girl) is as follows:
- average length or slightly longer is fine (again mentally they want to know they can "accept" a man fully - are a perfect match in their head)
- bit fatter than average is preferred and a bigger head is a bonus
- get turned on more by clean and trimmed
- just love it if it is rock hard and stays that way
- and the guy knows she can respond to lots of stimulation not involving his cock !!

So I would say
- dont get fixated about size ... In the same way it is silly for a girl to be fixated about her boob size only !!
- and you can't do / or shouldn't try .. To do anything about it...

BUT --- what you CAN DO .. is :
1) trim and be super hygenic (and I recommend shave/ wax your ball bag)
2) get hard / stay hard - and TELL her it is HER that does that to you !!!
3) use more than your cock - be inventive !
And don't think your mouth is just for licking and sucking !! Yes for kissing as well .. but just as important is for communicating ......

Of course all of this is a total waste of my time if all you want is to be pleasured and don't want it to be a mutual pleasurable experience regardless of context (wife / GF / fuckbuddy/ ML or WL)

Cheers