First of all, let me clear you that For admissions to UG programs, students have to pass 10+2 or equivalent examination with a minimum of 60% marks (55% for SC/ST candidates) in aggregate. So, as you have got 86.6% and even if your board of examination is state level, you will have no hurdle in this eligibility aspect while getting admission to Thapar University, considering the fact that you might have scored enough in JEE MAIN to clear the cutoff of CSE of this college.

You can check the cutoffs of Thapar University in detail by visiting our website through this link(below).

https://dqxeclau.top/university/thapar-institute-of-engineering-and-technology-patiala/cut-off

Hope it helps and do let me know in the comment section if you have any doubts left.