We would also like to see this added/restored.
If I remember correctly, there used to be a setting at tenant level in AAD that allowed changing the default minimum password length, but Microsoft removed it. We want to see this setting restored. We use a company managed password manager, along with MFA, so a longer password length would be a benefit (as we can monitor password strength).
We are using AAD only, with AAD joined devices managed by InTune MDM. Currently there is the option to set conditional access policy for password length at device level, but not the configuration. If we set the CA policy to 14 characters, then a user resets their password in a browser, which is governed by Microsoft's 365 setting of 8 characters, then the device gets marked as non-compliant and the user must reset their password again.
Microsoft's own recommendations in the security center recommend a minimum password length of 14 characters. The security center recommendation gives the remediation guidance of using a GPO, which we cannot do as we are AAD only.
Microsoft need to look at this urgently. It is a ridiculous situation for cloud only AAD joined and MDM device managed 365 users.