I can only hope this question is actually about a specific fetish or hyper vagina fetish or something idk, because otherwise I'd be a little concerned about anon's knowledge of human anatomy. (tone: non judgmental)
So this post got a little long (haha), but I figured since I don't know how much of this poll was a joke, and idk how much the average tumblr user does or doesn't know about sex ed, so I thought I'd play it safe. I figure it's better to be told something you(<general) already know than to go through life not knowing any of this at all, especially with how shit sex ed generally is. Bear with me.
Disclaimer: I am not a licensed obstetrician, gynecologist, midwife, or medical professional.
So for those who don't know, this kinda already happens. When aroused, the vaginal canal gets longer by a couple to a few inches (sources vary, gynecology is criminally understudied). The pelvic muscles also kinda lift the cervix up and out of the way, allowing for deeper penetration. Also, the muscles of the vagina and vaginal opening relax and "open up" when aroused, and the vagina and vulva together have multiple glands that excrete natural lubricant.
Fun fact, the average aroused vaginal depth is about 5-6 inches, while some studies say between 4-8 inches; and the average aroused penis length is about 4-5 inches.
This is why foreplay is so important, especially when getting penetrated with longer or thicker implements. Depending on the individual, if you're not aroused enough, you might have a lot of trouble even getting anything in there because your opening is not relaxed enough, you may not be wet enough, and your depth is gonna be a lot shallower than it would be if you were fully aroused. Feel free to experiment with vibrators, lube, fingers and tongues, and don't feel pressured to jam anything up there before you're ready.
If it seems like you can't ever be aroused enough for penetration, if it hurts, or you bleed, or you can't stay wet for long enough, you might want to look into dyspareunia, vaginismus, or vaginal atrophy, especially if you're peri or post menopausal, have lowered estrogen levels, or are on testosterone. I promise, nothing is wrong with you personally, you are not broken, and these are solvable problems.
It's also worth noting that repeated penetration does not and cannot alter the size, shape, width, or length of the vagina, nor can it alter the appearance of the vulva and labia. That's a misogynistic myth. Penises are not magic, they cannot change bodily tissues. Pregnancy and vaginal birth can temporarily change the vagina, but it should go back to normal after about 6 months, according to healthline. If it doesn't, talk to your OB/GYN about seeing a pelvic floor specialist.
