Essential topics to cover under Indian Polity for UPSC preparation include the Constitution of India, its features, and amendments. Candidates should focus on the structure and functioning of the Parliament, the Executive, and the Judiciary. Important processes such as fundamental rights and duties, the relationship between the Centre and states, and the role of various constitutional bodies like the Election Commission and UPSC itself are crucial. Moreover, understanding significant national and state policies enhances comprehension of the practical application of polity concepts.