Hello there,
The top IITs include:
IIT Madras
IIT Bombay
IIT Delhi
You need to score atleast 98+ percentile in JEE Advanced to get a seat in the top IITs. For CSE, you need to score atleast 99 percentile.
You can check the cut-off rank of various IITs in the link given below:
https://engineering.careers360.com/articles/jee-advanced-cutoff-for-iits
Also note that the cut-off rank changes every year depending on the difficulty of the paper,and the number of candidates appearing for it.
Hope this answer helps you.
Good luck!!