See if you have considerable concepts in the subjects then I would recommend you must study this books for KVPY:

• KVPY previous year question paper

• Concepts of Physics By H. C. Verma (11 and 12)

• Mathematics For Class XI & XII by R. D. Sharma
• For chemistry it would be good if you study the NCERT and if you can practice problems in Physical chemistry from P. Bahadur.

• NCERT 11th Biology Books & NCERT 12th Biology Books are enough for Biology. You can practice question of NEET.

To know more about KVPY books you may visit the link below:

https://school.careers360.com/articles/kvpy-books-know-best-books-for-preparation

I hope this answer helps. All the very best for your future endeavors!