Hey,
Firstly, Congratulations for passing 12th. Of you want to pursue degree in engineering then the best colleges are IITs and NITs without any doubt. For taking admission in these government Institutes, you have to clear the test of JEE which is divided in two parts JEE mains and JEE advanced. So you should prepare for that.
Even if you want to take admission in private University then they also require presence in JEE as eligibility. For private deemed Universities like

• VIT
• BITS

These Universities conduct their own entrance exams.
All the very best!