Hello aspirant,
A studebt can be from any discipline.UPSC Educational QualificationCriteria

The candidate must have at least a bachelor's degree from a recognised university to take theUPSC exam. ... Those candidates with professional/technicalqualificationswhich are recognized by the Government as equivalent to professional/technical degrees are also eligible.

The subjects studied will only help you upto a certain level. The rest solely and totally depends on you, your intetest, the strategy, weakness and strenghts.
All the best.