One plot twist might be that they form a secret alliance. In the normal Naruto story, their age difference and different story arcs keep them apart. But if they are the same age, they could work together to change the fate of the Uchiha Clan. They might come up with a plan that involves Sakura using her medical ninjutsu skills and Itachi's Sharingan powers in a way that no one expects. This would completely change the power dynamics in Konoha and how the other characters view them.
A possible plot twist could be that Sakura discovers Itachi's true intentions about the Uchiha Clan massacre much earlier. Since they are the same age, she might be in a better position to understand his motives or even try to prevent it. Another twist could be that Itachi sees Sakura as a potential threat to his plans because of her intelligence and strong will, which could lead to an unexpected conflict between them.
In some fanfictions, a plot twist could be that Sakura and Itachi end up falling in love. Since they are the same age, they have more opportunities to interact on a deeper level. This would be a huge change from the original story, as Itachi is usually portrayed as a distant and mysterious figure. Their relationship could cause a stir in the ninja world, with characters having to reevaluate their views on both Sakura and Itachi, and it could also lead to new alliances and enmities depending on how others react to their relationship.
One interesting plot twist could be that since they are the same age, they become rivals not just in power but also in terms of winning the affection of their peers. Naruto, with his boisterous and friendly nature, and Itachi, with his cool and mysterious aura, both vying for the same friends. Another could be that they end up in the same ninja team, which is unheard of in the original story. This would force them to work together and learn from each other's strengths, like Naruto teaching Itachi about the power of friendship and Itachi teaching Naruto more refined ninjutsu techniques.
Another plot twist could be that Itachi is under some sort of mind - control or illusion when he abducts Sakura. This could lead to a scenario where Sakura has to find a way to break the control on Itachi and in the process, they form an unexpected alliance. It would add an element of mystery and a chance for character development for both of them.
One possible plot twist could be that Itachi has been mind - controlled to kidnap Sakura. Maybe an enemy of Konoha has a powerful jutsu that forces Itachi to do this against his will. Another twist could be that Itachi kidnaps Sakura as a means to protect her from a greater threat in the shinobi world that no one else is aware of yet. He might know that she has some sort of power or knowledge that makes her a target, and by kidnapping her, he can keep her safe in a hidden location.
One possible plot twist could be that Naruto, being at Itachi's age, has already mastered some of the more advanced jutsu much earlier. For example, he might have learned the Sharingan - like abilities through some unique encounter, which would completely change the power dynamics in the Hidden Leaf. This would also lead to a different relationship with Sasuke, as Naruto would be more of an equal in terms of power and mystery.
Perhaps Sakura gets into trouble during a training exercise and Itachi has to rescue her, which then leads to a more intense and focused training regime. Another development could be that Sakura starts to think like Itachi in battle situations, using his tactics to outwit her opponents. It could also be that as she gets stronger, other characters start to notice and either become jealous or try to recruit her for their own purposes.
One interesting fanfiction could be 'Parallel Lives'. In this story, Sakura and Itachi being the same age creates a whole new dynamic in the Naruto universe. Their interactions are different from the original storyline as they are peers. For example, Sakura might be more involved in Itachi's early decisions, and Itachi could have a different view on Sakura's potential as a ninja.
A really interesting plot twist could be that Shisui and Itachi find out that Sakura has a connection to an ancient and powerful clan that they didn't know about before. This connection could bring in new elements to the training, like special techniques or a deeper understanding of the ninja world that they have to incorporate into her training.
One possible plot twist could be that Itachi's past actions as a double agent in Akatsuki are revealed in a new light because of the baby. Maybe his enemies try to target the baby to get revenge on him, but Sakura, being a strong kunoichi, defends the baby with all her might. This could lead to a series of battles and alliances being formed in the shinobi world to protect the new life.
In this fanfiction, a plot twist might be that Naruto returns to Sakura, but he brings with him a secret that could endanger the whole village. Sakura is then faced with a dilemma: whether to protect Naruto or the village. Or perhaps, Naruto returns to find that Sakura has made a powerful enemy while he was gone, and now they both have to deal with this new threat together. It could also be that Naruto's return is part of a bigger plan by an unknown villain, and Sakura gradually discovers this as she interacts with Naruto.
A plot twist could be that Sakura discovers Hinata has a hidden power that she has been suppressing all along. This power could be related to a long - lost clan ability, and it changes the dynamic of their relationship as they explore how to use it.