Apparently, there were 2 reports submitted to the Danish Ministry of Justice regarding 'pornographic pictures of children' or PBB, one in 2010 and one in 2017. Both reports cite various studies that show no evidence of PBB leading to 'contact-assault' on children. And when it comes to fictional PBB, this is what the reports concluded:

“Documentation supporting that ‘possession or similar of fictional child porn, that is not a realistic depiction, that appears in the same way or somewhat the same way as photographs or similar, can lead persons to commit sexual assaults on children’, does not seem to exist at the current time.”

“To conclude, there is to our knowledge still no scientific studies that directly casts light on the presented questions. Therefore, there is also no documentation that use of fictional pictures of sexual assaults on children, or use of sex-dolls that look like children, i.e. use of materials produced and utilized with actual children being exposed to violations, alone can lead people to commit sexual assaults on children. Research furthermore indicates that people who exclusively deal with pornographic pictures of children has a lower risk of recidivating, and a small risk of being convicted of contact-assault, compared to those who already has convictions for contact-assault and pornographic pictures of children. Whether possession of fictional pornographic pictures of children and/or sex-dolls increases or decreases the risk of new criminality, we know very little about at the current time.