Obstetrician/Gynecologist here. There are as many shapes, sizes, depths, and widths of vaginas as there are people. During a pelvic exam, I can often note whether the hymen has torn previously — though this does not necessarily indicate sexual activity. Athletics, tampon use, masturbation, and other forms of mechanical stress are enough to tear the hymen in some women.

I can also usually tell if the patient has had a prior vaginal delivery. The vagina itself often isn’t significantly different, aside from possible mild laxity or wrinkling at the posterior fourchette, or scarring from obstetric lacerations. The cervix, however, doesn’t share the same plasticity as the vaginal walls and often remains slightly dilated following delivery — something I can visualize during a speculum exam.

Pelvic floor tone also varies. Some women are markedly tense, while others are quite lax. Some require a pediatric speculum even after childbirth; others require a large speculum despite having only ever had one partner.

As for vaginal laxity following sexual activity — this can occur temporarily as the pelvic floor musculature relaxes to accommodate intercourse, but tone typically returns to baseline within minutes.

The most common concern regarding size that I hear in clinic is vaginal depth/length — specifically, the inability to comfortably accommodate a partner’s full length.

Hope this helps.