Well, she could be rescued by her friends. Maybe Naruto would use his shadow clone jutsu to climb the tree and get her down.
Another possibility is that it could be a start of a mystery. There could be something strange about the tree that she's stuck in. It might be a magical tree that only allows certain people to be freed, and she has to figure out the secret to escape. It could also lead to a discovery of an ancient power or artifact hidden within the tree.
In this fanfiction, it might be that the sakura on the tree is the last remaining one in a desolate land. A group of adventurers come across it. They then decide to protect it from the harsh environment and any potential threats. They build a small shelter around the tree to shield the sakura from strong winds and try to find a way to make the land fertile again so that more sakura can grow.
A wandering poet could be the main character. He is always in search of inspiration and when he sees the sakura stuck on the tree, it stirs something within him. He decides to stay near the tree and write poems about the sakura, and in the process, he also tries to find a way to free it if it's in some sort of distress.
They could use their ninja skills to try and break out of the box. Naruto might try his Rasengan, while Hinata could use her Gentle Fist to find weak points in the box's structure.
One possibility is that they start arguing at first. Draco, being his usual snarky self, might blame Hermione for getting them into this situation. But as time passes, they could gradually start to understand each other better. They might share some of their deepest fears and secrets, which they would never have done in normal circumstances.
In this kind of fanfiction, Sasuke might capture Sakura for various reasons. One possibility is that he wants to use her as a bargaining chip against Naruto. Another could be that he has some kind of misunderstanding and thinks Sakura is a threat to his plans. However, Sakura is not a weak character. She might try to reason with Sasuke during her captivity, appealing to their past friendship. Maybe she could even find a way to escape on her own or with the help of some unexpected allies.
There could also be a romantic plot. Maybe the person who finally rescues her is someone she has feelings for, or this event could be the start of a new relationship. For instance, a new character could come along and save her, and they start to fall in love during the process of getting her down from the tree.
In such a fanfiction, Sakura might be used by Orochimaru for his experiments. He could be interested in her chakra or her medical knowledge. Maybe he would try to extract some special power from her or force her to assist him in his unethical research.
One possibility is that Naruto and the others would immediately start a search and rescue mission. They would follow Sasuke's tracks and try to figure out his motives. Sakura, on the other hand, might try to reason with Sasuke during the kidnapping. She could remind him of their past friendship and the bonds they once shared.
One possibility is that the lights start to flicker. This would add to the already terrifying situation. As the character is stuck, they might start to hear strange noises coming from outside the elevator, like scratching or moaning. They could also feel a sudden drop in temperature, which would send chills down their spine.
It could go in a different direction too. Naruto might reject Sakura's confession. He could still see her as a dear friend, but not in a romantic way. This would create a lot of tension between them, and Sakura would have to deal with the heartbreak. Meanwhile, Naruto would have to figure out how to keep their friendship intact despite the awkward situation.