Yes, your class 12th score will be included in admission at Thapar University. Earlier admission was given on the basis of JEE Main rank and 12th board score in PCB/PCM. The division of seats was around 70% and 30% respectively.
But the Thapar Institute had recently revised its admission policy for admissions in the BE/BTech programs. As per the new criteria, 100% of the seats will be allotted on the basis of scores in the Class 12th examination. The student can check the deadlines on the official website of the college.