Dear Aspirant,

Yes you can take admission in the iits or nits after giving the JEE main and advanced exam. However, you will get the admission in the first year of btech and not in the second year like you do in state colleges.

You can read more here:-

https://engineering.careers360.com/articles/how-prepare-for-jee-main

https://engineering.careers360.com/exams/jee-main

https://engineering.careers360.com/exams/jee-advanced

https://engineering.careers360.com/articles/jee-main-syllabus

Comment if you have any doubts.

Hope this helps. Thank you.