Can art which is encouraging harmful behaviors possibly ever have the potential to result in people engaging in or continuing to engage in those behaviors? Or is this completely impossible?

So, while this is a "general" question, it seems likely that most people will gravitate towards themes of porn and sexual violence when thinking about it. Let me discuss from that perspective.

To be clear, I am not an expert, but it is something I have thought a lot about in the context of my field in technology (noting how generative AI can be used to create very graphic images depicting non-consensual activities).

The short answer: we don't concretely know for certain. There is an argument that giving people an "outlet" means they can satisfy an urge without endangering themselves in real life. There is also an argument that repeated exposure can dilute/dull the sense of social caution and normalise the fetishised behaviour.

I am very sympathetic to the former argument where it applies to acts between otherwise informed/consenting individuals. For example, a gay person in a foreign country with anti-gay laws; being able to explore their sexuality through the medium of 'normal' gay pornography seems entirely reasonable to me (but might seem disgusting by other cultural standards).

When it comes to non-consensual acts, I think there is a lot more room for speculation and concern. I would recommend reading this study as an example, which explored dangerous attitudes towards women that were shaped through pornography.

Some key takeaways:

1. It's never as simple as saying "porn caused it". There are a multitude of factors.
2. Regardless, there is a seemingly strong anecdotal connection between violent pornography and violent attitudes in real life.
3. It likely depends heavily on the individual and their own beliefs/perceptions/experiences before this development

And a final noteworthy line:

The view that pornography played a role in their clients’ harmful attitudes and/or behaviours was undisputed; what was harder for them to articulate was the strength of the contribution of pornography, given the complexities of the other contributing factors in their clients’ lives.

Not directly enough that you can draw a link between a piece of art and someone's action. People have tried to blame bad actions on games, movies, shows, rock music and rap music for ages without getting any substantial traction.

But all media does influence and normalize thought patterns. This is why advertisements and promotional campaigns exist and work, why war propaganda exists to bolster or harm morale and unity, why grisly horror movies are restricted from small children, and why people who are raised Christian have more faith in Christ than people raised Buddhist.

Can you find a link that someone raised on American movies, news, conversations, and comics are more likely to call for using deadly force on a burglar instead of someone raised in Finland? Very likely. Could you make the argument that "Home Alone 3" caused Steven to shoot and kill a confused drunk who went to sleep in the wrong house? Absolutely not.

Depends on the person. A person with sociopathic tendencies is gonna listen to a song glorifying violence or play a video game doing the same and see it as encouragement. But that’s also only the really stupid and violent, and those people were probably going to do those things anyway.

I think most people that find justification for violent actions from art would find other reasons to justify those things if they didn’t have the art to blame it on.

Why am I suspecting this is about AI generated art and offending pedophiles/[other problematic groups]?

This is a specific enough topic that I don't think it's fair to try and answer it in a general manner. Art affects people... but it doesn't directly lead to imitation - Doom and Counter Strike didn't spawn a generation of soldiers. But were a few people considering it and their experiences convinced them the final few steps? Probably.

Either way art is a good thing and people are more stubborn than you'd assume. If someone chooses to do something art didn't make them do... did it significantly influence them? I'd want to know specifics before commenting further.

Yes art can be used to influence people's actions. Art is commonly used in propaganda and advertising, which can and have caused people to do harmful things to others and even themselves.

When Mortal Kombat first came out and people were worried about the violence in it, my friend told me "If some kid rips off someone's head because he saw Sub Zero do it, there was something wrong with him to begin with.

So, not impossible, but people have been doing crazy shit long before video games/social media/TV/movies/porn/radio/books/art/music have existed.

Yes Karl Marx's "Das Capital" has led to hundreds of millions dead people.