Unless you are at a highly competitive, admission-by-exam-only school, similar to what Boston Latin used to be, or Bronx Science, or Stuyvesant, then top 15% at an open admission public school, even in a very good district, is not Ivy level. Every public school that has to take all comers is going to have a significant proportion of kids who aren’t serious students, so even in the best of districts, you can figure that only about 25% of the students are hard-working, high-achieving. Many valedictorians with perfect standardized test scores do not get into tippy-top schools, or even other Ivies. Being in the top 15% from a public school that is not an exam school is not that high a rank, and the top schools will know this. They have to be able to differentiate among all those 4.0UW applicants from your school. The school will send out something that reveals what “channel” you are in, in some way that enables the colleges to recognize your approximate rank.
I’m not saying that you shouldn’t apply to top schools. You should. But you have to spend more time focusing on choosing your safety and true match schools, because that’s very likely where you’re gonna wind up getting in. Then choose some low reaches, and some high reaches. And perhaps Penn or Rice ED as your dream school. You are allowed to decline if they accept you, but with insufficient money.
If money is an issue, if you’re in that sour spot where your family has an income in the 100-200K/yr range, or owns rental property, or farm land, or a business with real assets that could be mortgaged, you may be unpleasantly surprised that the school expects your parents to pay more than they are able to. Luckily, in-state UT tuition is a bargain. And if you want to do your parents (and hence yourself) a favor, add in applications to places where you might get a lot of merit money, as others have recommended.