Hi koushik

Hope you are doing well

For IAS purpose I will recommend any Bachelor course in social science stream

Here you get the combination of economic and political science subjects which will helps you alot

Alternatively, Bachelors in Public Administration/Public Policy is a good choice as “public administration” is the main job of an IAS officer.
...

• Pol sci.
• Geography.
• Sociology.
• History.
• Economy.
• And literature id have intrest it may give you edge over optional papers as long as it is in the syllebus.