I hope you are doing well,
Class 12 cbse board syllabus covers the syllabus for VITEEE and is enough to crack but getting a good rank solely on basis of that is a difficult task. I would suggest that you go through previous year papers of VITEEE and prepare accordingly.
Although the entire syllabus is covered in cbse but there are certain portions like organic chemistry for which you have to look up other reference materials. Personally I find CBSE books lacking in depth material to prepare for any competitive exam held in India
For maths, practice as much as you can. The more you practice, the better you get. Calculus and vector has a good weightage. Make a list of all the important formulas.
For chemistry, working on organic part is recommended. Practice the reactions properly. Physical chemistry is quite easy.
For physics, practice numerical and give importance to magnetism, electrostatics and modern physics. Other chapters are important too but I found these chapters a bit more important.
Do solve previous year VITEEE question paper which will help you in getting familiar with the paper.
Best Of Luck.