Hello Aspirant,
Yes if you read NCERT textbooks properly and thoroughly then you can easily get 100-120 marks in JEE-Main but if you are seeking more good marks then you should also read from some reference books because there are no sufficient question to practice in NCERT textbooks and for JEE-Main like entrance examinations you should have good practice of different types of questions so for your reference I am enlisting down some best books for preparation of JEE-Main 2021 :-

@Physics
Concepts of Physics-H. C. Verma
Fundamentals of Physics-Halliday, Resnick and Walker
Problems in General Physics-I. E. Irodov
University Physics-Freedman and Young
Understanding JEE physics series-DC Pandey
Problem In Physics-SS Krotov

@Mathematics
Higher Algebra-Hall and Knight
Coordinate Geometry-S.L. Loney
Differential and Integral Calculus-N. Piskunov
Calculus and Analytic Geometry-Thomas and Finney
IIT Mathematics for JEE Main & Advanced-M.L. Khanna
Course in Mathematics for IIT-JEE-Tata McGraw Hill publication
Problems Plus in IIT Mathematics-A Das Gupta
Trigonometry-S L Loney

@Chemistry
Modern Approach to Chemical Calculations-RC Mukherjee
Organic Chemistry-Solomons and Fryhle
Concise Inorganic-J. D. Lee
Organic Chemistry-Morrison and Boyd
University Chemistry-Freedman and Young
Physical Chemistry-N Awasthi
Arihant's Practice Book Chemistry for JEE Main And Advanced-R.K Gupta

You can also check out the JEE-Main knockout package for preparation of JEE-Main from the link given below :-
https://learn.careers360.com/knockout-jee-main-april/

I hope this information helps you.
Good Luck!!