The top colleges will be familiar with your school and grading system. High Schools have made an art of obscuring the class rank. But there are ways they can figure your estimated rank 1) Prior years and current year distributions from your HS 2) Counselor letter of recc and 3) Informal interactions with your HS guidance office.
Bottom line is that: the colleges know who the top students are from each high school, even those who don’t rank. But don’t worry top 25% is nothing to sneeze at. Just set your sights accordingly. Shooting for Harvard Princeton and Yale seem unlikely with a rank in the top 25% (unless you’re a recruited athlete or kid of a big donor).