Hello Aspirant,

Yes of course you can appear for JEE-Advance 2021 at most because only two attempts are allowed for JEE-Advance after passion class 12th so one attempt you will use this year and note that you will not be eligible for 2022 and for JEE-Main you can give for it at most three attempts so in your case you can give it upto 2022.

However you can use JEE-Main College Predictor to predict your admission chances on the basis of this year's result :-

https://engineering.careers360.com/jee-main-college-predictor?icn=QnA&ici=qna_answer

I hope this information helps you.

Good Luck!!