You can have the official UPSC syllabus from internet from this site
https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.upsc.gov.in/sites/default/files/Notification-CSPE_2020_N_Engl.pdf&ved=2ahUKEwjG3KeP2I3rAhWPxTgGHbsmAdcQFjAEegQIAhAH&usg=AOvVaw3sW7av8x5LFzTIvcsZho2-

And Yes, exams can be in English and Hindi.
Dono languages mein de skte hain. But English is compulsory examination.
refer the above complete notification for clarity.
Ask if have any doubts.

UPSC Syllabus and Language Options

UPSC (Union Public Service Commission) is the central agency responsible for conducting various prestigious exams in India, including the Civil Services Examination. The Civil Services Examination is conducted to recruit candidates for various administrative services in India, such as the Indian Administrative Service (IAS), Indian Police Service (IPS), and Indian Foreign Service (IFS). The UPSC syllabus for the Civil Services Examination is comprehensive and covers a wide range of subjects.

UPSC Syllabus

The UPSC syllabus for the Civil Services Examination consists of three stages:

1. Preliminary Examination: This stage consists of two objective-type papers, each paper carrying 200 marks. The papers include General Studies Paper-I and General Studies Paper-II (also known as the Civil Services Aptitude Test or CSAT).

2. Main Examination: The Main Examination is a written examination consisting of nine papers, including an essay paper, four General Studies papers, two Optional papers, and two language papers (one English language paper and one Indian language paper).

3. Interview: The final stage of the Civil Services Examination is the interview stage. Candidates who clear the Main Examination are called for an interview by the UPSC. The interview carries 275 marks.

Language Options

The UPSC offers candidates the option to choose between English and any one Indian language for the language papers in the Main Examination. The Indian language paper tests the candidate's ability to read and write in the chosen language. The Indian language options include Assamese, Bengali, Bodo, Dogri, Gujarati, Hindi, Kannada, Kashmiri, Konkani, Maithili, Malayalam, Manipuri, Marathi, Nepali, Odia, Punjabi, Sanskrit, Santali, Sindhi (Devanagari script), Sindhi (Arabic script), Tamil, Telugu, and Urdu.

Conclusion

In conclusion, the UPSC syllabus for the Civil Services Examination is vast and requires candidates to have a deep understanding of various subjects. Candidates can choose between English and any one Indian language for the language papers in the Main Examination. Candidates must prepare well for all three stages of the examination to clear it and secure a position in the prestigious administrative services of India.