As a school peer next year in high school, how can I do my bit and leave a worthy legacy? I am going to be a powerful voice for my school peers, and I would love to be inspired by ideas that would help change and comfort students at my high school next year.
That sounds like a great goal. I think you are taking a step in the right direction by asking for help too. Great leaders are not afraid of seeking help and getting advice.
I don't know what school you are at, nor do I do know the general "feel" of the current student body. What might work at the school I teach at, might not apply at all to your school.
Your question states that you want to be a leader for your peers. You want to make changes that positively affect your peers. You can start that process by asking your peers what they would like to see happen. It does you no good to make changes that you think are good, if the entire student body disagrees with you.
Keep in mind that you are going to get unrealistic suggestions. Things like "teachers should stop giving homework" and "the cafeteria should only serve chocolate" are unrealistic. I would argue that those are both bad for the student body too. You also need to be aware that you are going to get a bunch of good suggestions from the student body. You can't possibly accomplish all of them, so the responsibility falls on you to choose which changes are best and able to be accomplished.
Now for the bad news. Because you have to pick and choose which tasks to pursue and changes to make, you are going to make some people happy and some people unhappy. You need to realize right from the start that you can't make everybody happy. If you try to do that, you will leave a lot of people unhappy.
My other suggestion for finding inspiration is to look at other schools that you think "are doing it right." What do they have or do that your school doesn't? Would implementing those things work at your school, and are they even feasible? Good luck!