There isn't any good data to support or refute that, but the correct pronoun for a transgender woman is she/her unless she says otherwise. The US federal government has commissioned a study to examine a link between gender dysphoria, transgender identity, and violence, but even before it's begun there are serious questions about it's methods that would likely prevent it from being peer reviewed or replicated which would make it worthless scientifically.

I saw in other comments you were meaning that allowing a transfem prison to either transition or continue their already in progress efforts, but no one could say with any authority how that would effect levels of violence. In US prisons violence is an intentional feature rather than something the powers that be would prefer to mitigate. Threats of physical and sexual violence and their application serve the interests of the prison industrial complex which seeks to punish criminals and deter would be ones.

The US employs punitive justice and the suffering of those who are incarcerated is the point. Denying transgender prisons the ability to maintain their transition serves that goal, but also is a relatively safe way of stripping rights away from transgender individuals in a way that can seem unsavory to defend for a large portion of the US population which serves authoritarian political interests.