1. She has no idea how powerful she is. But they do. And they’re coming.

This isn't really a hook, more of a logline. The difference isn't always clear cut, but you can usually think of a logline as the words that might appear on a movie poster. Hooks are going to be more specific. You want to introduce your MC and something about them. They can often be originally phrased as "When... then" statements (and then reworked into something more interesting). "When MC experiences inciting incident, then they must react accordingly." Either way, you want your hook more grounded in specifics than what you have here. I'm also always leery about saying the MC doesn't know something. Usually we as the reader are discovering things along with the MC. Unless you've got a second POV that lets the reader in on information that the MC doesn't have, I would strongly advise against the "MC is unaware of something" line of writing, and even then I still think there are generally better ways to go about it. Use the fact that the MC has no idea about something as part of the hook. Characters trying to figure out what the heck is going on is usually solid hook position.

2. Nature’s survival hinges on her actions. But all 16-year-old Rhea is worried about at the moment is avoiding the school bully.

This is better, because we have the MC introduced and something that she wants. I would label this as an adequate hook, as in it would probably get the job done, but it doesn't leap out at me, and we can probably go stronger. The first sentence is a little too wide open for my taste, and again it falls into that territory of the MC not knowing something. What is the inciting incident for your story? When does Rhea realize something wonky is going on in her life? Use that moment that her life starts going haywire as the moment that hooks the reader. After all, as someone who reads spec fic (which this appears to me), I'm not looking to read about a teenage girl avoiding bullies. I'm interested in that moment when some commandos in masks try to kidnap her from school or when a mysterious stranger hands her a book saying she must protect it at all costs or whatever is that inciting incident for your story. That's what's going to get my attention. So lead with that.

Good luck.