After installation, go to Inventory >> Configuration >> Settings, in that activate Product Packagings option from Product Catalog section.

To see the manufacturing and Replenish on Order (MTO) Route in Product ,need to configure the Multi-Step Routes ,for that Go to the Inventory >> Configuration >> Settings >> Warehouse >> Multi-step Routes option.

Then after, create product with following configuration. 1) Product must be Storable Product and update onhand quantity, 2) Add different variants and update quantity for the variants, 3) Set Manufacture and Make To Order checked (To generate manufacturing order from sale order)

Now configure different variants. Update on hand quantity and add packaging options. You can use this option in sale order line form to select package according to quantity.

To create manufacturing order from sale order, then set BOM for the product.

Now go to Sales and create sale order with configured product and fill quantity and select package. You can see there, automatically calculate number of packages to be generated for this product.

Now click on Confirm button, to create manufacturing order.

You can see one transfer order generated.

Now go to manufacturing order, you can see one manufacturing order generated. Here you can see Sale Order and Sale Order Line reference and number of packages.

Now, produce items

Then after, click on Mark as Done, to fill transfer order with product packages and done quantity.

You can see transfer order product reserved with quantity and automatically filled quantity to each generated package

You can see packages generated with auto filled done quantity