NCERT books can help a lot to prepare for JEE Mains Chemistry. But it is not sufficient.
Inorganic Chemistry is the most scoring part. And for this section, NCERT books are a must. In past years there were questions directly from NCERT. But read your class notes and textbooks as well.
For Physical and Inorganic Chemistry, NCERT isn’t enough. You need to practice a lot, in order to have a good command of these sections. For these sections, go through the NCERT, make notes for important sections and solve practice series.
Yes, NCERT books are enough for the JEE Mains Chemistry. About 80% of the questions in the JEE Mains Chemistry are from NCERT directly. If you would have read NCERT properly you would be able to solve 65% easily.
But as JEE Main is a competitive exam, not everything will come from NCERT. Therefore, it is suggested you go through other books as well.
Lastly, it can be said that NCERT is a huge help when it comes to chemistry be it physical, inorganic or organic chemistry. Read topics like Biomolecules, Chemistry In Everyday Life, Polymers and Colloids from the textbook also.