If you invite users to Odoo via the out of the box functionality, there is no password until they choose it.  They are directed via URL to a page where they choose a password - so you may not need what you ask.

See also https://www.odoo.com/apps/modules/9.0/res_users_password_security/

This module allows admin to set company-level password security requirements and enforces them on the user.   It contains features such as

• Password expiration days

• Password length requirement

• Password minimum number of lowercase letters

• Password minimum number of uppercase letters

• Password minimum number of numbers

• Password minimum number of special characters
  
  

Out of the box it isn’t possible to force a user to change his password. However it is possible to urge them to change their password by notification or e-mail. If you really want to force them to change their password when they first login the only possibility is to build a custom module that has this functionality.