There are some women that enjoy vaginal penetration with the Great American Challenge. I've seen quite a few home made video clips of women enjoying feeling "filled up" by that big toy. They don't take in more than 7.5" of length though, which is no shock to me. That toy is too long for vaginal penetration. Only a tiny percentage of women could take it in deeper than 7.5".
A reasonable percentage of women enjoy feeling their vagina stretch around thick toys. I'd say that 25% to 33% enjoy that. If they gradually explore this type of fun, over the years they will gradually be playing with larger toys, when they go for stretching play. This is especially true if they have a partner that is also into big toys, and isn't intimidated by big toy play.
Big dildos do not permanently stretch the vagina. They simply make it more flexible. In other words, the woman's limit of what she can take in will be increased, but her vagina will still feel the same to her lover. It takes truama and tearing to permanently loosen the vagina. Thinning of the muscles around the opening also makes the vagina feel looser.
So, women don't worry about making your vagina loose. Explore with big dildos if you are curious about how it feels to feel totally filled up.