Well, one possible plot could be that Naruto discovers a new jutsu specifically designed to counter Madara's powerful Sharingan abilities. This jutsu might be related to the Sage of Six Paths' power that he already has. With this new power, Naruto engages in a series of intense battles with Madara, each time getting closer to figuring out Madara's weaknesses.
In the fanfic, perhaps Naruto teams up with some unexpected allies to fight Madara. For example, he could join forces with some of the previous Hokages who are still able to lend their strength in the spirit world. Together, they come up with a strategy that involves using Naruto as a distraction while the others work on sealing Madara's power.
The fanfic could also focus on a more psychological battle between Naruto and Madara. Naruto, being the optimist he is, tries to reach out to the good in Madara. He believes that there's still a part of Madara that can be redeemed. So, instead of just fighting physically, Naruto also tries to have conversations with Madara during the battle, which adds an interesting layer to the fight.
A practical answer is Chapter 162, because it turns the idea into a concrete scene. The chapter opens with He Yun then realized what was happening and subconsciously wanted to check..., adds pressure through Why mention someone else in Wanwan's live stream?, and ends on Having heard the news.
Chapter 142 is the strongest chapter-level answer because it starts from The ingredients for making Buddha Jumps Over the Wall were still on their... and follows through on Wen Jiaojiao immediately lit up and stepped forward to hug Jiang Li's arm..
A practical answer is Chapter 146, because it turns the idea into a concrete scene. The chapter opens with Director Sun: "???" Jiang Li smiled and said, "In the past, the show crew..., adds pressure through Otherwise, if they hog all the spotlight, what will we do?, and ends on That way, they.
The best chapter pointer here is Chapter 166, "Daniu Gets Jealous!". It opens with Only after everyone in the small courtyard had left, did Zhao Lang stride... and closes on However, after interviewing the villagers, no one has gone missing, so we....
A practical answer is Chapter 121, because it turns the idea into a concrete scene. The chapter opens with Seeing that Wen Jiaojiao's condition had improved significantly, Director..., adds pressure through How the hell was it a huge muddy field?!, and ends on You're supposed to be a man who.
If you want the clearest chapter reference, go to Chapter 97. Early on, Suddenly, Jiang Li's livestream room was packed with people, and the...; later, the chapter leans on [I came from Weibo's trending topics, is Master Jiang really that awesome?.
If you want the clearest chapter reference, go to Chapter 109. Early on, And another thing," Jiang Li said, taking out a tissue to wipe her lips,...; later, the chapter leans on The next time we have a meal, don't try to chat with me unless you're fine....
Look to Chapter 138 for the clearest answer. It begins with Is there such a good deal?, keeps building through Qi Tianyu quickly nodded in agreement and knelt down to start helping..., and lands on Could it be that the poison also had a side effect of making a person more....
If you want the clearest chapter reference, go to Chapter 126. Early on, Wen Jiaojiao initially wanted to cause trouble.; later, the chapter leans on But when her gaze swept around and landed on Jiang Li, who was standing at....