Well, in a Naruto changes the past fanfiction, it might change the power balance. Naruto could use his future knowledge to make Konoha stronger earlier. He could teach new jutsus to the younger generation sooner or even prevent some of the big battles from happening. This would lead to a very different ninja world where perhaps there would be more peace and less conflict among the villages.
Perhaps he would change to Naruto Storm. 'Storm' can represent his powerful and sometimes tempestuous nature. In the series, Naruto has shown great strength and determination that could be likened to a storm, which is both destructive and at the same time a force of change.
One common plot is Naruto preventing the Uchiha massacre. By doing this, he not only saves Sasuke's family but also changes the relationship between the Uchiha and Konoha. Another plot is Naruto stopping Orochimaru from getting too powerful early on, which could prevent a lot of chaos in the ninja world.
Often, the theme of self - discovery is present. By changing the past, Sakura gets to learn more about herself and her capabilities. Also, the theme of preventing a tragedy is quite common. Maybe there was a big disaster in the original timeline that she aims to avoid. In these fanfictions, the exploration of the butterfly effect is also a thing. Every change she makes in the past has consequences in the future, and this can lead to interesting plot developments.
At first, Naruto might become more secretive. He'd be hiding his new 'profession' from his friends, which is very different from his usual open - natured self. This could cause some internal conflict as he doesn't like lying to them.
He could be teamed with Shino. Shino is very calm and collected, and his insect - based jutsu could offer a different kind of support compared to Naruto's usual teammates. Together, they could develop some really interesting combat strategies.
There could also be some minor characters that become more important in this fanfiction. For example, Harry's parents, James and Lily. Since Harry is changing the past, they might have more of a role to play. Or perhaps characters like Sirius Black or Remus Lupin could be involved in different ways due to the changes Harry makes in the past.
Another plot might be Harry changing his relationship with Snape. He could go back and try to understand Snape better from the start, which might lead to a very different dynamic between them. This could potentially change how Snape behaves towards Harry and the other Gryffindors, and also how Harry views Snape throughout his time at Hogwarts.
I'm not sure of specific 'sakura changes the past fanfiction' titles off - hand. You could try searching on fanfiction websites like Archive of Our Own or FanFiction.net. They usually have a large collection of fanfictions on various topics.
The contents of the Spring Festival's Eastern Mountain Rebellion were: Chapter 1: Blood and Yellow Soil in the Imperial Palace, Chapter 2: Thunderstorm, Chapter 3: The World Shakes, Chapter 4: Abandoned Crown Prince, Chapter 5: The Sovereign of the East Sea, Chapter 6: The Crescent Moon Shines on Eastern Mountain, Chapter 7: Fleeing to the Furious Sea, Chapter 8: Pursuit, Chapter 9: A Stunning Spear, Chapter 10: Great Grandmaster, etc.