There are several options for the next of kin to be able to do that, but the first way would be to mail or fax a Request Pertaining to Military Records Standard Form SF 180 to the National Personnel Records Center.
Are there other ways besides milConnect to acquire my own records?
You can mail or fax a Request Pertaining to Military Records Standard Form SF 180 to the National Personnel Records Center, you can write them a letter and mail it to their Missouri address or you can visit their office in person. You can also hire an independent researcher.