Hii!
UPSC exam consists of all round subjects such as physics, chemistry, basic mathematics, economics, geography, history, literature, general knowledge, current affairs etc., Specifications are tested for different posts at a later level. In order to know the syllabus, you can either visit the UPSC official website or refer the link given below -

https://www.google.com/amp/s/competition.careers360.com/articles/upsc-ias-syllabus/amp

Hope this helps.
Good luck!