Yes, there are likely some fanfics out there with such a plot. Fanfic writers often explore alternate storylines, and this would be a very dark and dramatic deviation from the original Naruto story.
One possible 'naruto sasuke death fanfiction' could be where they die in a final battle against an extremely powerful new enemy that neither of their powers could overcome. This new foe has abilities that nullify their jutsu and in a heroic but tragic attempt to defeat it, they sacrifice themselves.
One possible reason could be that he overestimated his abilities during a battle in the Wave arc. Maybe he took on an enemy that was much stronger than he thought and got fatally injured. Another reason could be that he sacrificed himself to save Naruto or someone else. It's also possible that there was some sort of betrayal within the group they were with, and Sasuke was caught off - guard and killed.
Well, Naruto's death would likely shatter Sasuke. He has always had Naruto as a sort of anchor, whether he admitted it or not. His whole life has been intertwined with Naruto's. Naruto's death might make Sasuke question his entire purpose. He could initially be filled with rage and a thirst for revenge, thinking that he could have prevented it. This could lead him down a darker path at first. But eventually, it might also make him realize the importance of Naruto's ideals and he could strive to carry them on in Naruto's memory.
One popular 'Naruto and Sasuke death fanfiction' might be one where they sacrifice themselves to save the Hidden Leaf Village from an ultimate evil. In this kind of story, their deaths are seen as heroic and a way to bring about lasting peace in the ninja world.
Well, if Sasuke dies in this fanfiction set in the Wave arc, Naruto would likely become more determined to avenge him. He might also grow more solemn and focused on his ninja training, realizing the fragility of life. His view of the world could shift from being a bit more carefree to a darker, more serious one as he grapples with the loss of his friend and rival.
Often, their deaths are portrayed as heroic. For example, they might die while saving the Hidden Leaf Village from a catastrophic threat like a massive invasion by a powerful and evil ninja force.
He might be shocked. In the fanfic, if he sees things like his friends' future achievements or the new threats that emerge, it would surely startle him. For example, if he discovers that one of his friends has a family of their own and has become a great leader in the village, he would be proud but also a bit surprised at how much has changed.
Maybe Sasuke goes too far in his pursuit of power and tries to harm someone Naruto cares about deeply in the Forest of Death. Naruto, in a fit of rage and to protect the person, kills Sasuke.