Is it a good idea to work with a CA firm after B.Com for future growth as in salary and position in Accounts and Finance?

If you are interested in doing accounting job then you can do a job under CA firm and after that, you can do a job with a company regarding accounting.

If you want to work with a CA firm, you must have knowledge about the CA stuff. B.Com and CA are two different things. B.Com is about business and management, whereas CA is about accountancy.