Well, initially, her friends would be stunned. Harry would be at a loss for words. He'd be thinking about all the times they had together and how Hermione's appearance was part of who she was. Ron would probably blurt out something insensitive in his shock. But as time passed, Harry would start to see that Hermione was still the same person inside. Ron would slowly come around too, especially when he realized that Hermione's decision was more complex than he first thought. Ginny would be the one to really help Hermione feel accepted, reminding her that her true self was more important than her new look.
One possible plot twist could be that Hermione gets plastic surgery to go undercover in a wizarding world where appearance is crucial for a mission. Maybe she has to infiltrate a group that only accepts people with a certain look. Another could be that she gets plastic surgery due to some kind of spell gone wrong that affected her appearance and she's trying to reverse it through muggle means as a last resort.
Olaf would try to make Anna laugh. He would tell his silly jokes and do his goofy dances. He would also try to keep Anna warm with his carrot nose. He might even build a small snowman inside the room to keep Anna company when everyone else is busy.
Ginny would be very empathetic. She'd probably try to understand Hermione's situation from a female perspective. Ginny might try to get some female friends or relatives to help out, like bringing food or warm clothes to Hermione. Luna would be her usual unique self. She might think that Hermione is on a special spiritual journey and would offer her some very strange but oddly comforting advice.
Harry would be extremely worried and determined to find a cure. He'd probably search every corner of the library and consult all his wizarding contacts. Ron, on the other hand, would be initially in shock but then would try to cheer her up with his clumsy humor.
Her friends would likely be very shocked and worried. Some might rush to the hospital immediately and stay by her side, constantly checking on her condition. For example, her best friend might be in tears and refuse to leave until they know Bella is out of danger.
Hermione's friends would likely be very excited. They might plan some special activities for her parents. For instance, they could arrange a little tour of the Forbidden Forest (from a safe distance, of course). They would also share stories about Hermione at Hogwarts, how smart she is and all the adventures they've had together. And they would be happy to answer any questions Hermione's parents had about the wizarding world.
Harry and Ron would probably be shocked at first. Ron might be a bit scared, but Harry would quickly see the potential in Hermione's new ability. They would likely be proud of her for achieving such a difficult transformation and would support her in using it for good.
She might be initially shocked. After all, she would have trusted her friends a great deal. Then she could become very sad and withdrawn. She might throw herself into her studies even more as a way to cope, trying to distract herself from the pain of losing her friends.
After the initial reactions, Hermione may choose to isolate herself for a while to figure things out. She would use this time to study and research, trying to find a solution to the problem with her friends. She might also look for new allies or resources within the fanfiction world to help her deal with the situation.
She might be initially shocked and hurt. Hermione is a character who values her friendships deeply, so their sudden departure would be a big blow. She could spend some time in denial, not believing that they would actually leave her.