For my course, will I get the additional 24 months extension under STEM OPT in USA?

No, you would not be eligible for the additional 24-month STEM OPT (Optional Practical Training) extension in the USA with a degree in Business Administration.

The STEM OPT extension is only available to students who graduate with a degree listed on the U.S. Department of Homeland Security's STEM Designated Degree Program List, which typically does not include Business Administration.

If you have a prior STEM degree from a U.S. institution within the last 10 years, you may qualify based on that earlier degree. Otherwise, the extension does not apply.