This module is used to create invoices, posts, and send emails automatically when validating the sale order. It is only possible when the sale order has no online payment and product invoice policy depending upon the ordered quantity.

How Does It Function?

The entire process of creating invoices, posts, and sending emails automatically is mentioned below.

As demonstrated in the screenshot below, confirm the sale order, which has no online payment system. 

Once you validate the sale order, the automated functionality of this module will create and confirm the invoice automatically. Moreover, it allows the automatic sending of emails as well. 

https://apps.odoo.com/apps/modules/15.0/ksc_auto_invoice/