hi alok,

I hope you are doing well. Regarding 81 percentile, it will not fetch you a good rank. Your rank will be more than 2 lakh. Last year JEE Mains cutoff for general candidate was 89 percentile. This year also it will be around 89 percentile and will not change drastically. So as you are not even clearing the cutoff so its impossible for you to get a good college with this percentile. So now what you have to is: Prepare well for the upcoming JEE Mains because almost all tier-1 college accept candidates on the basis of JEE Mains. Also prepare for some state level exams as a backup option.

I hope this answer will help.
All the best for the future!!