Hello there! IITM has removed the branch change system, so you cannot branch change from BS in Medical Science & Technology to other B.Tech. programs. To read more about the reason for this decision and what students can do instead, check this post.
If you wish to explore careers outside your branch, there are numerous options in the form of electives, minors, and Interdisciplinary Dual Degree (IDDD) programs. In addition to that, IITM students, who are curious about a new field or want acquire new skills, attend summer schools and undertake internships.
Furthermore, IIT Madras is launching many student-friendly initiatives, including courses in entrepreneurship, minors in all departments, elective-only semesters, that will encourage more students to learn outside their core domain and exert academic flexibility even without branch change.