Hi,

In Odoo 18, the stock.picking record is created when a sale.order is confirmed through the method action_confirm() in the sale.order model. Specifically, when you confirm a sale order, Odoo triggers the creation of a corresponding stock picking to handle the delivery process. This is done via the stock.picking creation logic in the sale.order model, which internally calls the stock.picking.create() method from the Stock module, with the relevant details about the products and quantities to be delivered. This process is part of the core flow and can be found in the sale_stock module, which integrates sales and stock management.

Hope it helps