Effective communication skills enhance interview performance for UPSC candidates by allowing them to articulate their thoughts clearly and confidently. Candidates who express their ideas well can present their viewpoints, knowledge, and understanding of complex issues effectively. Strong interpersonal skills can also foster a positive rapport with the interview panel, showcasing their personality and suitability for the civil services. Additionally, the ability to listen actively and respond appropriately to questions can significantly improve their overall impression during the interview.