One possible plot implication is that it could create a rift between Naruto and some of the shinobi in the village. Since the Sharingan is an Uchiha - specific power, some might be suspicious of Naruto having it. Another is that it could lead to Naruto being targeted by those who want the Sharingan for themselves.
Well, Naruto already has his own powerful abilities like the Nine - Tails' chakra. But with Shisui's Sharingan, his perception skills would be enhanced. He could probably anticipate attacks better and maybe even use some basic Sharingan - related genjutsu. However, it would also be a challenge for him to master as he has no prior experience with the Uchiha's dojutsu.
One plot implication could be that Naruto becomes an outcast among some in the village who fear the power of the Sharingan. This would create internal conflict within Konoha. Another is that Naruto might be targeted by enemies who want to either steal the Sharingan or kill him to prevent him from becoming too powerful. Also, it could change his relationship with Sasuke, as they both now share a connection to the Sharingan.
Well, if Shisui gives Naruto his Sharingan in the fanfiction, Naruto's perception abilities would likely skyrocket. The Sharingan can see the flow of chakra, so Naruto could detect enemies more easily. He might also be able to copy some jutsus more effectively, just like Sasuke and Kakashi can with their Sharingan. However, Naruto would have to learn to control this new power as it might conflict with his own natural chakra control methods.
A simple plot could be that Itachi entrusts Naruto with his Sharingan because he believes Naruto can use it to bring peace to the ninja world. Naruto, being the kind - hearted person he is, accepts the responsibility. He starts training with Kakashi to understand and master the Sharingan's powers. With the Sharingan, Naruto can anticipate his opponents' moves better and uses this advantage in battles against powerful enemies like Pain.
In fanfiction, Shisui's Sharingan often has some unique abilities. It's usually depicted as having powerful genjutsu - related powers. For example, it might be able to cast illusions on multiple opponents at once with greater ease compared to a normal Sharingan. His Sharingan can also potentially be used to transfer memories in more creative ways in fan stories, like not just the basic memory transfer we saw in the original Naruto series but perhaps more complex emotional and skill - based memories.
This would be a huge change for Naruto. Firstly, the Sharingan's ability to see chakra flow would let Naruto analyze his opponents' weaknesses more accurately. He could potentially use this to improve his Rasengan or develop new jutsus. Moreover, in terms of combat, he could enter genjutsu battles on a more equal footing, which was something he previously struggled with due to his lack of natural genjutsu skills.
In some fanfictions, Shisui's Sharingan has a different color or pattern. This is a simple but effective way to make it stand out. For example, it could be a deeper red or have an extra swirl in the pattern.
Well, the plot could start with Itachi realizing that Naruto is the key to the future of Konoha and the ninja world. So, he gives Naruto his Sharingan. Naruto then has to deal with the new power. He might start having visions related to Itachi's past, which could help him understand the Uchiha - Senju conflict better. And this new knowledge could influence his decisions in future battles and political situations in the ninja world.
In some fanfictions, it could be through a special jutsu or ritual. Maybe Itachi, before his death, transferred his Sharingan to Naruto in a unique way, perhaps using a forbidden technique that was known only to a few in the Uchiha clan.