Hello Komal!

Don't worry about that right now. Even if you will get less than 75 then there are some government colleges suitable as per your percentile which admit students with less than 75 in their personal level local counselling. But that's just a backup plan for you to stay calm. Try your best in the primary rounds of counselling and look for better colleges but as of now, stay calm.

All the best

Right now all you need to do is calm down. Just think positive I am sure that if you have scored 85.6 percentile in JEE mains then definitely in boards too you will do well. As of now there is nothing that we can do but however in case you land in a situation where your board percentage is below the minimum required then you may consider taking up improvement exams, but that will only happen at a later stage, for now let's hope for the best.