Well, in a Naruto time travel future fanfiction, a plotline could be Naruto finding himself in a future where the chakra system has been completely disrupted. People are suffering because of this. He uses his time - traveling knowledge to find a way to fix it. Another idea is that he travels to a future where the five great nations are at war again, but this time it's a more technological and brutal war. He has to use his experience and charisma to stop the war and bring peace once more.
One possible plotline could be Grogu traveling back to the time of the Jedi Order's prime. He could meet the great Jedi Masters and learn from them directly. This would be amazing as he could gain more knowledge and skills, and it might also change the course of his own future.
One possible plotline could be Megatron traveling back in time to prevent his own creation. This would create a paradox as his actions in the present are a result of his past self. Another could be him going to a time when the Autobots were at their weakest and trying to finish them off once and for all.
One possible plotline could be traveling back to the time of Julius Caesar. The protagonist could get involved in the political intrigue, perhaps even influencing the events leading to Caesar's assassination. Another could be going to the height of the Roman Empire and experiencing the grandeur of the Colosseum, interacting with gladiators and senators.
One possible plot twist could be that Naruto and Jiraiya travel back to a time when the Uchiha clan was at its peak. This would put Naruto in a position to potentially prevent the Uchiha massacre. He could use his knowledge of future events and his skills to change the course of history for the better. Jiraiya, on the other hand, could discover secrets about the Uchiha that were lost over time.
One possible plot twist could be Naruto changing the past in a way that completely alters the future relationships. For example, if he prevents a certain event that led to a character's death, it could change the whole dynamic among the characters. Another twist could be that Naruto discovers that the past is not as simple as he thought, and there are hidden forces at work that he didn't know about in his original timeline.
One interesting plot could be that when they time travel, they end up in a time before the Uchiha massacre. Itachi could then try to change things with Naruto's help, and in the process, their relationship deepens in a yaoi way. Maybe Naruto helps Itachi see a different path for the Uchiha, and they grow closer as they face the challenges together.
In some fanfictions, Naruto time - travels and ends up being adopted by the Uchiha family. This gives him a whole new perspective on the Uchiha's situation. He then uses his position to try and prevent the misunderstandings that lead to their destruction. There are also fanfictions where Naruto travels back to meet Madara Uchiha as a young man. He tries to change Madara's view of the world and stop him from starting the cycle of hatred that plagues the ninja world.
One possible plot twist could be that Narukaka travels back in time and accidentally changes a small event that has huge, unforeseen consequences in the future. For example, preventing a minor meeting between two people that was supposed to lead to a great discovery.
One of the most interesting plot twists could be that Naruto discovers a new form of chakra that has the power to rewrite history. This would completely change the power dynamics in the Naruto universe.
Well, perhaps a really cool plot twist is that Naruto and Shizune time travel to a future version of the ninja world that is on the verge of destruction. They then have to figure out what went wrong in their own time to cause this and find a way to prevent it from happening. Or, they could travel back to a time when Orochimaru was still a good guy, but their presence somehow starts to corrupt him, leading to a whole new set of problems. Another idea is that they time travel and end up in the body of other characters, which is really strange and they have to adapt to these new identities while also trying to find a way back to their normal selves and their own time.