Vagina feels loose after masterbating for the first time. the object was only an inch wide. is this normal? what surgery can reverse this?

Masturbation: You don't need surgery. The area may be loose right now but will likely pull back into shape (although not necessarily to exactly the original tightness).

Vagina: Typically the vagina can have some laxity. The normal size of the vagina is variable the following article from Oxford Academic should help: https://academic.oup.com/humrep/article/21/6/1618/724374. Another article of benefits would be the following: https://helloclue.com/articles/cycle-a-z/vaginas-101

No surgery: This is normal, as the vagina is a muscle and can change shape to accommodate, up to allowing a baby's head! And still goes back to it's normal shape. If you feel concerned, you can do Kegel exercises to strengthen the muscle. You do not need surgery for this at this time.