Are there any courses similar to MIT OCW to learn all courses from IITM

Yes! The National Programme on Technology Enhanced Learning, or NPTEL, is an initiative spearheaded by the IITs and IISc which includes a catalogue of more than 2400 courses taught by professors from these institutes.

Access to all these course lecture videos and assignments is completely free- you only need to pay if you wish to appear for an in-person course exam to be officially certified.

Most professors at IITM offer NPTEL courses - and several of these are even recorded in classrooms with IITM students who are enrolled in the in-person, IITM equivalent of the course.

You can visit https://nptel.ac.in/ and https://swayam.gov.in/ to find out more about this.