Yes, there might be. The 'fanfiction' world is vast and diverse. There are often crossovers that combine different popular franchises in unexpected ways. However, the quality and nature of such a fanfiction can vary greatly. Some might be really creative, while others could be a bit of a mess.
In some Highschool DxD and Naruto crossover fanfictions, Naruto might be depicted as a god - like figure. This could be due to his extremely powerful abilities in the Naruto universe, such as his vast chakra reserves, multiple jutsu, and his status as a hero in his own world. Writers may take these aspects and amplify them in the Highschool DxD setting, where the power levels and the concept of beings with god - like powers already exist. So, it's possible for Naruto to be seen as a god in such fanfictions.
If Naruto was a god in Highschool DxD fanfiction, he would likely change the power dynamics completely. His abilities could overpower many of the existing characters in the Highschool DxD universe. For instance, his speed and strength, enhanced by his god - like status, would make him a formidable opponent in battles. He might also attract a lot of attention, both from the good and the bad characters in the story, as his power would be a great asset or a threat.
A good plot idea could be that the OC Dragon God has to hide their true identity in the high school. They are there to find a certain magical item that is hidden in the school. As they search, they get involved with the main characters and have to deal with the normal high school drama as well as the supernatural threats that come their way.
One aspect of Highschool DxD x Male Sex God fanfiction is how it can re - imagine the harem aspect. Since he is a sex god, the way he approaches relationships with the female characters could be very different. Instead of the typical high school romance - like interactions, there could be a more mature and intense connection. He might also have a different view on loyalty and love compared to the regular characters in the Highschool DxD world.
It would probably be really interesting. Naruto's skills and abilities as a 'god' would likely disrupt the normal flow of the Highschool DxD world. Maybe he'd use his ninja techniques in battles against the devils and angels in that universe.
Rias could also be a popular character. She is a powerful devil and her leadership skills could be put to the test in a story that combines Highschool DxD with the God of War. Maybe she has to negotiate with the God of War characters or lead her group against a common enemy from that realm.
Power - up is a common theme. Since Issei becomes a Dragon God, the fanfictions often explore his new powers and how he uses them to overcome challenges. Another theme is relationships. His relationships with other characters, like Rias and his friends, might change due to his new status.
It could be about the characters having to create their own moral code in a world without a divine being to guide them. Maybe the devils and angels would have to re - evaluate their long - standing enmity and find new ways to coexist.
One idea could be exploring a new Godly power that the main character discovers within the Highschool DxD universe. Maybe it's a power that has been long forgotten and its emergence shakes up the existing power dynamics among the devils, angels, and fallen angels.