How to create a purchase order from a sales order?
2 methods are available as you can read in the Odoo docs > https://www.odoo.com/documentation/16.0/applications/inventory_and_mrp/inventory/management/products/strategies.html.
Before Odoo 14.0 there was only MTO ...
- Create a product, check ‘Replenish on Order (MTO)’ and the Buy route on the inventory tab and add a vendor in the purchase tab.
- Create and confirm a sales order with the product => a purchase order is created automatically.
Since Odoo 14 MTO is hidden (warehouse route is archived) and can be reactivated or replaced by using reordering rules > https://odootricks.tips/odoo-14-replenishment-mto/.