I disagree. There is no evidence deterrence works, and I think it's very unlikely that there are people who want to commit sexual assault who would decide that it's not worth the risk if more people were punished. I don't think people work that way.
If you are thinking about citing the Italian study[0] that people always cite in respond arguments against deterrence. My response is that it's way more likely that 1 month less in prison is what caused the lower re-offending rare, not the threat of 1 month more in prison if they re-offend.
[0]: https://www.journals.uchicago.edu/doi/abs/10.1086/599286
Prisons can and should do better. But you are incredibly naive if you think there aren't people in the world whose only deterrence is prison or violent retribution.