Yes, there might be such fanfics out there. In the Naruto fandom, with a large number of fans creating various types of stories, it's possible that some would write a story where Naruto destroys Sasuke in a way that could be seen as Sasuke - bashing. However, these kinds of fanfics may not be in line with the overall spirit of the original work which focuses on their complex relationship and growth.
One possible theme could be revenge. If the writer is bashing Sasuke, they might have Naruto seek revenge on Sasuke for his actions in the original story, like when Sasuke left the village. Another theme could be power display, showing Naruto's overwhelming power as he destroys Sasuke.
In this fanfiction scenario, Naruto might be able to destroy Sasuke during the Chunin Exams due to his own growth and newfound abilities. Maybe he has mastered a new jutsu that gives him an edge over Sasuke. For example, if Naruto has fully harnessed the power of the Nine - Tails at this point, his strength could be overwhelming.
One common theme could be redemption. Even though Naruto is 'destroying' Sasuke, it could be seen as a way to save him from a path of self - destruction. Another theme might be power struggle. The idea that Sasuke's pursuit of power has led him astray and Naruto, with his own power, has to put an end to it. Also, friendship could be a theme. Naruto might be doing this out of a sense of love for his friend, that he can't let Sasuke continue down this dark path.
For Naruto, he would have to grapple with the fact that he is fighting his former friend. This could make him more solemn and determined. He might develop a darker side as he realizes the seriousness of stopping Sasuke. For Sasuke, he could start as overconfident in his power but as Naruto keeps pushing him back, he could become more desperate and start to question his own motives.
One possible plotline could be that Naruto, having a fundamental difference in ideology with Sasuke, decides to take a stand. Maybe Sasuke is on a path that Naruto believes will destroy the village or their friends. So Naruto uses his newfound powers, perhaps a combination of Sage Mode and Nine - Tails chakra, to directly confront Sasuke. Naruto could try to break Sasuke's resolve through sheer force and the power of their friendship memories.
Maybe in this fanfic, Sasuke has gone too far in his quest for power and revenge. He starts attacking innocent people or trying to take over the Hidden Leaf Village. Naruto, as the hero, has no choice but to stop him. Naruto could use his talk - no - jutsu at first, but when that fails, he resorts to physical combat. He might start with his basic Rasengan and gradually level up his attacks as Sasuke counters with his Chidori and other powerful jutsus. In the end, Naruto destroys Sasuke's evil intentions and either kills him or imprisons him, depending on the tone of the fanfic.
It could be Sasuke. If he were to turn to the dark side in the fanfiction, his Rinnegan powers could be used to destroy Konoha. He has the potential to be extremely powerful and if he has some sort of vendetta or is influenced by some dark force, he might take his anger out on the village.
Sasuke might be able to stop Naruto. They have a long - standing relationship and Sasuke has always been Naruto's equal in terms of power. He could use his Sharingan to try and break whatever is controlling Naruto or just fight him head - on and appeal to their old friendship.