It is a privilege, not a right. Because of that, each state has unique procedures, and rights and obligations, which have to be followed. A lawyer must be consulted in each case. Other states prohibit that contact, or at least will not require such visitations. As in child custody matters, it is the child's best interest, in the judgment of a court, that will govern whether an adoption will occur, and whether there will be visitation in those states that allow visitation.
Adoptions are often through agencies.
Again, this varies from state to state. In other states, private agencies can broker adoptions. Perhaps needless to say, that practice has led to much abuse, and is now under close regulation by those states that permit it. It happens, and a parent has responsibility for that. Only a lawyer can assist you with the answers to these questions, and preparation of the adoption paperwork and underlying agreements, if any.