One plot idea could be Naruto using his newfound time - stopping ability to prevent a major disaster in Konoha. For example, he could stop time just as a powerful enemy's ultimate attack is about to hit the village, and then find a way to counter it while time is frozen. Another idea is that Naruto uses it to have some peaceful moments with his friends and family that are always cut short in the normal flow of time. He could share a meal with his dad, Minato, and have a long conversation that was never possible before.
One idea could be Naruto using his time - control ability to go back in time and prevent the Uchiha massacre. This would completely change the course of the Naruto universe, leading to different alliances and power dynamics. For example, Sasuke might not have the same drive for revenge, and the Akatsuki's plans would be disrupted as Itachi would not be a rogue ninja.
One idea could be Naruto going into the time chamber to train for a new, extremely powerful jutsu that no one has ever seen before. He could emerge with this jutsu and use it to defeat a powerful, new enemy that threatens the Hidden Leaf Village.
A really interesting plot would be if the male OC's time - stopping power has a limit. He discovers that every time he uses it, it drains his energy and he has to find ways to replenish it. This could lead to him having to make difficult choices about when and how often to use his power. Maybe he has to form an alliance with a magical being that can help him manage his power in exchange for some favors. And all this while, he's also dealing with the normal high school drama in the DxD universe like dealing with rivalries and making friends.
One idea could be Naruto going back to the time of the First Hokage to prevent a dark jutsu from being created that later causes chaos in his own time. He could use his knowledge of future events and his powerful jutsu to stop the wrongdoings.
One plot idea could be that Naruto, while pregnant, travels back in time to the founding of Konoha. He uses his knowledge of the future to prevent certain tragedies from occurring during the village's creation, all while dealing with the physical and emotional challenges of being pregnant in a different time. Another could be that he travels to a time when the Uchiha clan was still intact and tries to change the events that led to their downfall, with his pregnancy adding an extra layer of complexity as he has to protect his unborn child too.
One idea could be Naruto using his time - skip ability to go back and prevent certain tragedies in the ninja world, like the Uchiha massacre. He could change the course of history and create a more peaceful future from the start. Another could be that he skips forward in time to see the potential outcomes of his actions in the present, and then uses that knowledge to make better decisions in the current time.
One idea could be that Naruto travels back in time and gets adopted by a different clan. For example, the Uchiha clan. This would change his whole upbringing and how he views the world. He might learn different jutsus earlier and have a different relationship with Sasuke.
A cool plot idea could be Minato traveling back to his own childhood. He could then use his future knowledge to train himself more effectively, making himself an even more powerful shinobi at a younger age. This would have a huge impact on the future of the Leaf Village as he would be able to better protect it earlier. He might also be able to prevent some of the early tragedies that happened in the village.
One idea could be Tobirama traveling to the future and seeing how his village has developed. He might be shocked by the new technology and the different ninja techniques. Another plot could involve Tobirama going back in time to change a crucial event in Naruto's past, like preventing the Uchiha massacre. Or perhaps he travels to a different timeline altogether and has to find a way back while dealing with that timeline's unique challenges.
One idea could be Naruto traveling back in time and meeting Hashirama. He could learn about the founding of the village directly from Hashirama. Maybe Naruto helps Hashirama deal with some early threats to the village that were not well - documented in history.