There's a possibility she'll encounter powerful sages or hermits living in the mountains or deep in the forests. These wise beings might have knowledge about chakra manipulation that is far more advanced than what she has learned in Konoha. They could help her unlock new levels of her own chakra and give her the strength she desires.
Sakura could also run into other female shinobi from different villages who are also on a journey of self - improvement. Together, they could form a sort of sisterhood, sharing their knowledge and experiences, and training together to become stronger. This would not only make her physically stronger but also give her a different perspective on being a female shinobi in the ninja world.
She might meet some rogue ninjas. Some of them could be good - hearted but on the run from their villages for unjust reasons. They could teach her some unorthodox fighting techniques that are not taught in Konoha.
One potential plot could be that Sakura travels to different hidden villages and learns unique fighting styles from their top shinobi. For example, she might go to the Sand Village and study under a master of puppetry, adding an unexpected skill to her repertoire.
He might encounter a hermit who lives in a tree and has some really strange habits. The hermit could offer Naruto some 'wise' advice that is actually just really absurd, like telling him to walk on his hands to find his true path.
For Naruto, it would be a big shock. He's always seen Sakura as an important part of the team. He would probably feel guilty, thinking he might have done something wrong. Sasuke might be more reserved in his reaction, but deep down, he would also feel the loss. Kakashi would be worried about her safety. The other ninja in Konoha might start to question the unity of the village if someone like Sakura, who was so well - known, left. And the young ninja who looked up to Sakura would be disappointed and might even lose some motivation in their training.
She could meet a wise old hermit who has been living in seclusion for centuries. This hermit could possess great knowledge about spiritual powers and could teach Kagome how to enhance hers. Another potential character is a powerful warrior from a different tribe. They might initially be hostile but later become friends and train together.
She might meet a friendly librarian. The librarian could be an old, wise woman who has lived in the town all her life. She would show Sakura all the interesting books about the town's history and introduce her to some of the regular library visitors, which could be the start of Sakura making new friends.
Sasuke might initially be shocked. He has always seen Sakura as someone connected to Konoha, so her leaving would be unexpected. He could be concerned about her safety, especially if she leaves without proper preparation or protection.
He might meet Gaara. Since Gaara is the Kazekage of Suna, it's very likely that they would cross paths. Naruto and Gaara have a history, so their encounter could be filled with reminiscing about their past battles and how far they've come.
One possibility is that Sakura leaves Konoha to seek stronger medical ninjutsu training elsewhere. Maybe she's heard of a hidden village with advanced medical techniques and decides to leave her home to master them. This could lead to her facing new challenges, making new friends, and coming back to Konoha as an even more powerful and knowledgeable medical ninja.
Obviously Sakura herself is the most important character. Naruto and Sasuke would also be important as they are her friends and comrades. Kakashi could also play a role, maybe as a mentor or someone who gives her advice on how to readjust to Konoha life.
It could be that some of the village elders or leaders send someone to go after her. They might see her running away as a threat to the village's stability or as a potential loss of a valuable asset. Maybe they send a team of ANBU to track her down and bring her back, whether by force or persuasion.