This is a very big conception among the freshers who want to go for the UPSC CSE examination. See there is no such influence of your subject in the preparation of UPSC CSE. Every year a lot of Engineers, Doctors also become IAS officers and they are certainly not from the backgrounds like Economics, GEOGRAPHY etc. As a result, what ever the subject combination you wish, you can study. The eligibility criteria for the UPSC examination is that the student need to be a Graduate in any stream. So you can complete graduation in any stream of your choice and you can become an IAS officer provided, you must be sincere about the preparation of UPSC CSE. The preparation for the UPSC CSE is the main thing which matters the most for the success to become an IAS officer.

For more information regarding UPSC CSE preparation tips consider the link below:

https://competition.careers360.com/articles/how-prepare-for-upsc-ias

I hope this helps. Wish you a great day!