I m preparing for jee mains paper 2 i.e b arch paper. . So my question is is ncert is enough for maths part??

If you are also preparing for paper 1 then no extra study for paper 2 maths is needed by if you are only appearing for paper 2 then NCERT is okay but for good marks you should follow some others books like Arihant or KC sinha

In my experience Paper 2 has simpler Mathematics compare to paper1. You can study from NCERT and score well. If you are considering just NCERT that it is not enough that you are able to solve the exercise question. It means that you can solve questions base on that it may be higher than the NCERT level.

For good practice, I would recommend you to follow RD Sharma as it contains more details about each and every topic, so you will get most of the subjects and it will increase your problem-solving skills. Not just consider NCERT as benchmarks you need to go beyond that.

Please note that some of the Problems of the miscellaneous Exercise have a very good question so understand them properly, I have seen that sometimes even question come directly from that.