Hello GOVINDU SREEHARSHA1,
Thank you for posting in Microsoft Community forum.
You can read the link below.
Minimum Password Length auditing and enforcement on certain versions of Windows - Microsoft Support
And here is a similar thread with other suggestions you can try.
Enforce 15-character minimum password length on Windows - Server Fault
I hope the information above is helpful.
If you have any question or concern, please feel free to let us know.
Best Regards,
Daisy Zhou