The Phoenix Force in a Naruto fanfiction could change the entire Naruto universe. If Naruto were to gain the Phoenix Force, it could lead to a whole new era in the Hidden Leaf Village. His friends like Sasuke might be jealous or worried about this new power Naruto has. And the Akatsuki, if they were still around, would definitely be interested in getting their hands on the Phoenix Force, seeing it as a means to achieve their goals more easily.
In a Naruto - Phoenix Force fanfiction, Naruto might have to learn to control the volatile power of the Phoenix Force. He's used to his chakra, but the Phoenix Force is a whole different level of power. It could be a story about him struggling to balance his ninja way with this new, almost god - like power. He might even use it to bring back some of his fallen comrades, but at a great cost, like having to sacrifice some of his own life force.
Well, one idea for this fanfiction could be Naruto somehow getting connected to the Phoenix Force. Maybe it's during a mission in a strange dimension where he discovers the power of the Phoenix Force. It could give him new abilities like enhanced healing, which is similar to his own natural fast - healing ability, but on a much larger scale. And this new power could also attract new enemies who are after the Phoenix Force.
He could encounter it during a time - travel arc. Naruto gets sent to a different universe where the Phoenix Force exists. He quickly realizes its potential and tries to figure out how to use it without being consumed by its power.
He might need to train a lot. Just like he trained to control the Nine - Tails' chakra. He could start with small amounts of the Phoenix Force's power and gradually increase his control.
If Naruto got the Phoenix Force in fanfiction, his appearance might change a bit. Maybe he'd have some sort of fiery aura. His personality could also be affected. He might become more confident or even a bit more aggressive in battle. He could use the Phoenix Force to travel faster, too, like teleporting short distances.
One possible new jutsu could be the 'Force - Nature Manipulation'. Naruto loves nature and is already good at using nature - based chakra. With the force, he could go beyond just using chakra from nature. He could use the force to actually control natural elements like waterfalls, trees, and rocks directly. For example, he could make a whole forest move to his will, trapping his enemies or creating barriers. This would be a very unique and powerful jutsu that combines his ninja skills with the power of the force.
One possible fanfiction could be about Naruto finding a way to redeem Kaguya. He might use his unique ability to understand others' pain and show her a different path, away from her power - hungry ways.
One new ability could be Force jump. Naruto could use the Force to propel himself into the air much higher and farther than his normal jumps. Another would be Force sense, which would let him detect hidden enemies or traps more easily. He could also use the Force to influence the minds of his opponents on a minor level, like creating distractions or making them hesitate during a fight.
Naruto might develop a 'Force - Shadow Clone Jutsu'. He could use the Force to create shadow clones that are more durable and have some Force - related abilities. For example, they could use the Force to sense enemies or even share knowledge between each other more effectively.
In a more comical fanfiction, Ino could be trying to give Naruto a makeover. Since Naruto is not exactly known for his fashion sense. She might enlist the help of Sakura and together they turn Naruto into a more stylish ninja. This could lead to all sorts of funny situations, like Naruto trying to fight in his new fancy clothes or scaring off enemies with his new look.
One possibility could be that Naruto uses his ninja skills in the Kalos region. For example, his speed and agility could be very useful in Pokémon battles. He might also form unique bonds with Pokémon based on his own experiences of forming bonds with his comrades in the Naruto universe.
One possible fanfiction could be about a crossover where Naruto characters end up in the Highschool DxD universe. Maybe Naruto himself could attend the high school and use his ninja skills in the unique situations there. He might form new friendships or rivalries with the characters from Highschool DxD.