I asked this question recently thinking about my daughter, who got baptised at 14 but very quickly realised she had made an emotional decision and wasn't aware of all of the facts re. JW beliefs. So she hasn't validated her decision by continuing to act as a witness into adulthood. My question was motivated from a desire to see her avoid getting disfellowshipped and the pain and punishment of shunning which come with that.
When I asked the question on here someone pointed out to me that going through the process of requesting an anulment whether granted or not (unlikely) would inevitably lead to us being red flagged by the cong. and shunned anyway!