what will be my rank in jee 2021 if my percentile is 97.7 ??

Hello, based on your Paper-1 percentile your overall rank will be 23529 - 26450. This is a decent rank and you have chances of getting good colleges. Try a bit more hard in next attempt to get even better rank. You may get seat in top NITs, IITs & IIITs if you can boost up your rank.

You can use rank booster to boost your rank. I'm providing you with the link.
https://learn.careers360.com/jee-main-rank-booster/?icn=QnA&ici=qna_answer

To predict in which colleges you get seat use below link.
https://engineering.careers360.com/jee-main-college-predictor?icn=QnA&ici=qna_answer

Check out previous year's cut-offs using below links.
Cutoff-
https://engineering.careers360.com/articles/jee-main-cutoff

Official cutoffs for NITs, IIITs, IITs, CFTIs-
https://josaa.nic.in/Result/Result/currentorcr