Hi Priyanka,
The Prevention of Sexual Harassment (POSH) at Workplace Act is applicable to every workplace, establishment, company, or organization employing 10 or more employees (full-time, part-time, interns, or consultants included) irrespective of its location or nature of the industry.
If we closely review the above-referred applicability requirement, if your firm employs 10 or more employees, then POSH would mandatorily be applicable to your firm as well.