One possible main plot twist could be that Naruto discovers that the people forcing him to become daimyo are actually being controlled by an old enemy. This enemy wants to use Naruto's new position to gain power in the hidden villages. So Naruto has to figure out how to break free from this forced situation while also dealing with the political chaos that starts to unfold as a result of his new status.
It's possible that an outside force from another country is behind it. They want to weaken the Land of Fire by putting Naruto, a powerful and unpredictable element, in a position where he has to deal with political matters rather than ninja battles. They believe this will make the Land of Fire more vulnerable to their future attacks.
Well, Naruto would probably face a lot of challenges. He's used to being a ninja, not a daimyo. He'd have to adapt to a new lifestyle. He might try to bring his ninja values to the daimyo role, like honesty and loyalty. But the existing power structures in the daimyo's world might oppose him. And he could end up changing the whole political landscape in the process.
One possible plot twist could be that the Fire Daimyo has secret ninja skills. He might train Naruto in a different style than in the original series, which could lead Naruto to develop unique abilities. This would change the power dynamics in the Naruto universe.
One possible plot twist could be Naruto facing discrimination within the noble circles due to her status as the Daimyo's daughter but also being a female ninja. Another could be political intrigue where her position is used by enemies of the Daimyo to gain power. For example, they might try to kidnap her to force the Daimyo into making concessions.
One possible plot twist could be that Naruto has to face an unexpected opponent during the Chunin Exams. Maybe a rogue ninja infiltrates the exam and targets Naruto specifically because of his Nine - Tails power. Another twist could be that the rules of the Chunin Exams are suddenly changed in the middle, forcing Naruto to adapt quickly. For example, they might add a team - vs - team battle where Naruto has to work with his former rivals.
In a 'naruto fire daimyo fanfiction', the plot could involve the Fire Daimyo playing a crucial role in the politics of the Hidden Leaf. Maybe he has some secret plans to strengthen the alliance between the Leaf and other villages. He could also be a target for some enemy shinobi who want to disrupt the balance of power in the Fire Country.
Well, one possibility could be that the Daimyo of Sound decides to form an alliance with Konoha. He realizes that by joining forces, they can better protect their lands from common threats like the Akatsuki. So he sends envoys to Konoha to start diplomatic talks, which is full of drama as there are still some mistrusts on both sides.
In this fanfiction, perhaps the Daimyo of Wave is ill and there is a power struggle within his court. Naruto gets involved as he was once a hero in Wave. He tries to ensure a peaceful transition of power while also dealing with external forces who want to take advantage of the chaos. There could be epic battles and emotional moments as Naruto fights for what he believes is right for Wave.
Perhaps Naruto as Daimyo decides to create a new type of military force that combines ninja skills with traditional samurai training. This would lead to a whole new set of adventures as he has to train these new soldiers and face off against other regions' military powers. He could also use his charisma to form alliances with other Daimyos in a way no one else has before.
Well, in such a fanfiction, perhaps there's a political conspiracy behind forcing Naruto to be Hokage. Maybe some hidden group wants to control him through the Hokage position. Naruto then has to not only deal with the responsibilities of being Hokage but also uncover the conspiracy. He'd be constantly at odds with the council who forced him into this role, trying to prove that he can do a good job on his own terms.