For Engineering colleges admission in west bengal, the WBJEE rank only matter & nothing to do with the percentage of your 10+2. If you want to take admission in the General degree colleges, through Merit then while the institute assigns the Merit score, the previous year students gets some reduced percentage. But that's not at all the case for the WBJEE score accepting colleges. So if you are going to take admission in Engineering colleges, then only your WBJEE score will matter.

For more information regarding WBJEE you can consider the link below:

https://engineering.careers360.com/articles/wbjee

I hope this helps. Wish you a great eve!