If you wish to take admission in NIT, then you need to appear for the JEE MAINS examination and if you have sufficient enough rank then you will get admission in the NIT. Before, COVID phase, the board marks of 75% are required for the student in order to be eligible for the JEE MAINS examination. From 2020, it was waived. So if you have appeared for JEE MAINS this year, then your 10+2 marks won't matter at all, if you have good JEE MAINS rank, then you will get the NIT through JOSAA counselling.

For more information regarding JEE MAINS consider the link below:

https://engineering.careers360.com/exams/jee-main

I hope this helps. Wish you a great eve!