What is general question pattern set by IIT Madras?

There is no general question pattern set by IIT Madras. The paper is not just set and organized by a single IIT.

A number of professors are selected from every department of random IIT’s and they make the sets. Various sets of paper are made and finally, one is selected by the head of the committee.

It is a very common misconception that the paper is set by a single IIT so their professors can provide some insight into it. No guesses can be made regarding the paper, so give it your best shot and have faith in the preparation you have done.