One very simple approach is using the “Forgot password” functionality.
The users can technically do it on their own but also you can just go to the login screen, use the forgot password button and enter the mail of the user.
They will then get a new mail. Technically it is then a password reset mail and no longer an invitation mail (so it has a different text) but both give you a token to set a new password.
So in a multi tenant environment I used this.
In a single Tenant environment the forget password is an option but also setting a fixed password + User must reset password on next login. So if the user logs in with the provided password, he need to change it.