Well, in a fanfiction where Naruto is born the same age as Itachi, Naruto would likely have a different set of skills and experiences. Since Itachi was a prodigy, Naruto being the same age might mean he'd be pushed harder in his training. He could have been part of the same generation of shinobi that Itachi was. This would mean different interactions with the Akatsuki as well. He might have had to face off against them much earlier in his life, and his growth as a ninja would be shaped by these early and more challenging encounters.
If Naruto was born the same age as Itachi, the story would be drastically different. Naruto would be more mature and skilled earlier. He might have been involved in the Uchiha massacre situation. Maybe he could have even tried to prevent it, given his nature of not wanting to see people suffer. This would also change his relationship with Sasuke. Instead of being an older peer, he would be more of an equal in age, and their rivalry could take on a different dynamic, perhaps more of a mutual understanding from the start.
The fanfiction with Naruto born the same age as Itachi would rewrite a lot of the plot. Naruto would grow up in a different environment. He'd be in the same age group as the older, more advanced shinobi. This could lead to him having different mentors. Instead of Jiraiya, he might have been trained by someone else. His understanding of the ninja world's politics would also be different. He would be more aware of the Uchiha - Konoha situation from a younger age. And his bond with Sasuke would form under different circumstances, perhaps with both of them being more evenly matched in their growth and development from the start.
The best chapter pointer here is Chapter 275, "Five Defects and Three Shortcomings". It opens with Hu Zi was exceptionally cooperative, and within half an hour, all the... and closes on Since you two are considering the village, let's use this money to repair....
Look to Chapter 281 for the clearest answer. It begins with In his dream, he found himself in a strange world., keeps building through The upper half was fire, the lower half sea., and lands on Are you okay?" Jiang Yan covered his wound, the pain causing him some....
Chapter 276 is the strongest chapter-level answer because it starts from After listening to Jiang Li's words, Shen Lan's brow furrowed again. and follows through on Don't overthink it and get some rest." Jiang Li nodded..
A practical answer is Chapter 270, because it turns the idea into a concrete scene. The chapter opens with After liking the post, Jiang Mingyu put his phone away and turned back to..., adds pressure through Is he coming back from the dead?!, and ends on A moment later, he stood up, his expression.
The best chapter pointer here is Chapter 273, ""Justice Will Eventually Triumph Over Evil". It opens with Jiang Li, who was reading a book, suddenly jumped in fright. and closes on The two walked side by side in silence on an even quieter path..
If you want the clearest chapter reference, go to Chapter 238. Early on, Jiang Li was actually first on all three leaderboards?!; later, the chapter leans on Could it really be that outrageous?!.
The best chapter pointer here is Chapter 228, "Younger Brother is the Number One Hater?!". It opens with Huo Ziyang had not stepped out of the house for a whole week. and closes on Why did you hit Ziyang?" Huo Xuan, one hand holding a phone and the other....
The best chapter pointer here is Chapter 278, "Who Are These People Who Idolize Jiang Li?!". It opens with People from the fan club also got word that Jiang Li was soon to return to... and closes on How about we throw a party instead?" He Yun was more laid back, "You guys....
The best chapter pointer here is Chapter 236, "The Murderer Returns to the Scene of the Crime Theory". It opens with The short-haired youth beside them chimed in, "That's right, senior, we... and closes on Everyone, try not to get too anxious." The crowd nodded, seemingly....
A practical answer is Chapter 253, because it turns the idea into a concrete scene. The chapter opens with Wen Jiaojiao immediately lost her composure, leaping up from the bed and..., adds pressure through He then opened his phone, scrolled through the contacts to find Jiang Li's..., and ends on.