HI student,

See, UPSC IAS Prelims paper is an objective type paper so in that you have only English and Hindi as the languages but you can write the IAS Mains exam in Kannada as it is accepted by UPSC. But, the question paper of UPSC will be in English and Hindi only unless it is an compulsory language paper, so, you should have a good understanding of English or Hindi too.

Refer here for more info - https://competition.careers360.com/exams/upsc-civil-services-exam

Feel free to ask doubts in the Comment Section.

I hope this information helps you.

Good Luck!