Greetings!

No! They are not.

NCERT helps you to build concepts, understand the subject when you are studying it for 1st time, for better score in KVPY you must read some peripheral material for physics you have to read H.C. Verma for strengthening your concepts, solve the numericals from it, you may refer D.C. Pandey or any other book which is standerdized for IIT-JEE or Medical entrance exam preparation.

For chemistry, the case is similar to physics, reading organic in detail is more important here, inorganic and physical chemistry is more or less same in all books and is the matter of revision only, but organic chemistry needs some focused solving and practice to master, so better focus on it.

I hope this was helpful. Thank you!