I think that you are talking about jee advanced exam.
Now, for giving the jee advanced exam you first have to qualify the jee mains exam, and after that you will become eligible to give jee advanced.
For jee advanced the class 12th eligibility criteria of 75% has been scrapped. So, for jee advanced you just have to pass your class 12th exam.
You can also check out the following link to know more about jee advanced 2021 :-