Yes! UPSC allows the candidate to appear for the GS papers & the optional papers to be in different medium. So if you wish to write your GS in english & the other papers in Hindi then also its possible.

For more information regarding UPSC CSE you can consider visiting the link below:

https://competition.careers360.com/exams/upsc-civil-services-exam

I hope this helps. Wish you a great day!