hello aspirant,

YES, you can join UPSC after graduation in b.Com (//b.Com) or if you have attained at least 21 years of age.

Study subjects like History, Geography, General knowledge, polity, general science, daily awareness and as you are a Commerce student, you might as well opt for Commerce subjects as optional. Take mock tests. Go through previous years' question papers. After attaining 21 years of age, register for UPSC CSE .

further, yes, there is field in UPSC which is related to accounts. The UPSC IAS exam has Commerce And Accountancy as one of the subjects in the list of optional choices for Mains exam which has 48 subjects in total.

further, to know more about the UPSC Exam - eligibility criteria, subjects, admissions, etc - you can follow the below mentioned link to know more : https://competition.careers360.com/exams/upsc-cse

I hope that this will help.