Hello varun

JEE mains is one of the most important and hard exam, and syllabus is also vast

If you study for jee mains,you have to study all the 11th and 12th syllabus thoroughly and have to practice alot,sometimes 9th and 10th syllabus also helps,it means you have to put your all school knowledge to give this exam,so if you prepare for this exam you will perform good in any other engineering entrance exam,

But it's always good to go through model test papers of every entrance exam so that you will understand the pattern of exam and you can build strategy to finish in time and perform well.

Best of luck