Hello Aspirant,

Yes you will be able to write JEE-Main 2021 if you had passed your class 12th in 2019 or later on because as per the NTA the candidate can appear for JEE-Main for maximum of three years consecutively from the passing year of class 12th, whether you join any engineering college or not, you can appear for JEE-Main until all your attempts get over.

As of now in every year there will be 4 sessions which means that a candidate passing his/her class 12th in 2021 will get 4*3=12 total attempts for JEE-main.

For more details kindly check out the link given below :-

https://engineering.careers360.com/articles/jee-main-number-of-attempts

I hope this information helps you.

Good Luck!!