In the UPSC Mains essay paper, candidates can write on various types of essays, including analytical, argumentative, and reflective essays. Analytical essays require candidates to dissect and interpret a topic, evaluating multiple perspectives. Argumentative essays encourage candidates to defend a particular viewpoint with well-structured arguments. Reflective essays allow for personal insights or experiences related to broader societal themes. Themes often revolve around current issues, social challenges, or philosophical questions, necessitating a well-informed, coherent, and articulate response that demonstrates critical thinking and clarity of thought.