Hey there

For civil services just graduation is the eligibility and the exam is made such that no partiality is done for any branch. Like even for science stream you can take optional papers of your choice. For example if you have done electrical engineering then you can take electrical as your optional. But are serious about civil services then arts may be a good option as it would be centric to the exam only.

Check details about UPSC civil services

https://www.google.com/url?sa=t&source=web&rct=j&url=https://competition.careers360.com/articles/upsc-ias-exam-pattern/amp&ved=2ahUKEwjUs_2Y9ZzpAhWSzTgGHUpjBEAQFjADegQIBBAB&usg=AOvVaw2XfSBrsDpKF3HZZ36A91rO&ampcf=1

Good luck

Hello,

Eligibility for UPSC is graduation in any discipline from a recognized university, but as UPSC is more humanities oriented,you can take arts in 11th and 12th and thereafter in graduation.

But,let me tell you one more thing UPSC allows candidates from all backgrounds to appear for this prestigious exam, so in case you've other aspirations such as engineering, medicine,science you can still go ahead with this choice, in the past few years people from aforementioned backgrounds too have qualified IAS, this will also give you a back up plan.