It could have completely changed the dynamics of his battles and his relationships with others. The Sharingan would have given him an extra edge and new abilities.
If Naruto had red hair, it would likely have been a significant visual change. It might have influenced his personality traits ascribed by others or the way his skills and abilities were perceived. Maybe it would have added an extra layer of mystery or charm to him.
If Naruto had the Sharingan in fanfic, he'd likely become even more powerful. His combat skills would improve as he could use the Sharingan to predict his opponents' moves more accurately. He might also be able to use some of the unique jutsus associated with the Sharingan. For example, he could potentially learn to use Amaterasu if the fanfic writer allows for that kind of power combination.
Naruto might adapt by first trying to understand the basic functions of the Sharingan. He could start with the simple ability to see chakra flow more clearly. Since he has always been perceptive about people's emotions, he could use the Sharingan to read the emotions of his enemies through their chakra, which would help him in battles.
He might have increased visual abilities. For example, he could see chakra flow more clearly, which would be a great advantage in battle.
In a fanfic, Naruto with the Rinnegan and Sharingan would have a whole new set of challenges. He would have to deal with the jealousy and fear of other ninja villages. His own village might also be divided on how to handle his new powers. On the positive side, he could use these eyes to better understand the history of the ninja world. For example, the Rinnegan might give him insights into the Sage of Six Paths' true intentions, and the Sharingan could help him uncover secrets about his own family. He would also have to train hard to fully utilize the combined potential of these two powerful eyes, which could lead to some interesting training arcs in the fanfic.
If Naruto was an Uchiha, it could lead to interesting plot twists. Maybe he'd have a stronger sense of revenge or be more conflicted about his place in the ninja world. Also, his interactions with the other Uchiha characters could be very different.
Naruto as a Saiyan? That'd be insane! He'd have insane physical strength, the ability to go Super Saiyan, and it might even affect his relationships with the other characters in unexpected ways. The potential for adventure and excitement would be through the roof!
Well, when the Sharingan is neglected in fanfiction, it can lead to a less diverse range of powers and abilities being represented. The Sharingan has unique abilities like predicting movements and copying jutsu, and without it, stories may lack that kind of strategic and combat - related depth. Also, it can make the Uchiha clan seem less important in the fan - created Naruto universe, which goes against the significance they have in the original series.
Typically, in 'godlike sharingan naruto fanfiction', the sharingan has abilities far beyond what is shown in the original Naruto series. For example, it might be able to control time or space. The characters with these godlike sharingans are often the center of the story, driving the plot forward with their overpowered abilities.
In fanfiction, if Naruto has the Sharingan, it can change his relationships. He might have a different connection with Sasuke, who is originally associated with the Sharingan. Also, it could lead to new story arcs. For example, he may need to learn how to control this new power, which could involve training with characters like Kakashi who also has the Sharingan. It can also attract the attention of different villains or groups who are interested in the power of the Sharingan.