1. WinSCP implements SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ as defined in SSH spec:
   https://datatracker.ietf.org/doc/html/rfc4252
   So you have to find out how to make your server send this request.
   WinSCP will then show this Password change prompt:
   https://winscp.net/eng/docs/ui_authenticate#password_change
   
   
2. Fallback solution is to make use of SSH banner to let user know, he/she has to change the password:
   https://winscp.net/eng/docs/ui_authenticate#authentication_banner
   

Hi there, We have recently had to implement a 90 day max period before a user must change their password. However, the users are not warned of password nearing expiration date and therefore they are locked out.
We need to find a way to ensure that users change their passwords within winscp before it expirese.
Documentation that i have read implies that the server may request you to change a password, particularly if your password has expired but this is not happening.
Please advise on how to get winscp to prompt for password change.