Alright, I know everyone says HP essays are overdone and cliche and they should die off, basically. However, I really would love to write an essay on how Hermione’s character helped me gain confidence growing up as an overachieving immigrant black female in a very very white area. I thought that it would be more unique to talk about my experience while relating it to Harry Potter, because it really did shape me, but if you guys think it would be a mistake lmk.
Well, I think it is better to write about Hermione than Harry. 
One of my kids wrote about trying to imitate a famous literary character for years. It worked pretty well – there were serious topics, but also some self deprecating humor, and she could show how she had grown with and apart from her initial obsession with the character.
I think your challenge is how to make it mostly about you vs about her. You kind of have to assume your reader is familiar with the character to make it work; otherwise you spend a lot of space explaining them (not yourself), and you run the risk of falling flat if your reader hadn’t read HP (I definitely know adults who haven’t). The character my kid picked was VERY well known and from adult literature, so she didn’t have to do a lot of explaining. You might try to find a reader who hasn’t read or seen HP to try it out.
I’ve never read Harry Potter.
Would your essay still make sense to me?
In the end, it’s not the subject matter that matters that much. It’s how you use it as a vehicle to make a compelling PS. You could write about warm milk if you wanted to, as long as it conveyed something potent (it would be surprising, but not impossible to conceive).
With that said, however, I agree with the above posters. Don’t fall into the trap of having to explain the character more than you explain yourself.