What citizen’s charters and codes of conduct should I know for UPSC?

You should master the Citizen’s Charter as a tool for "Quality, Choice, and Standards" in public service, focusing on its six core principles.
Use Sleepy Classes’ Governance modules to differentiate between the Code of Conduct (enforceable rules/don'ts) and the Code of Ethics (aspirational values/do's).
Prioritise the Nolan Committee principles and 2nd ARC recommendations to understand how these frameworks ensure transparency, minimize red tape, and institutionalize professional integrity within the civil services.