Reference:
https://docs.microsoft.com/en-us/business-applications-release-notes/april19/dynamics365-finance-operations
/uom-by-variant

See explanation below.
Explanation
When you configure Direct Delivery (direct from the Vendor), a PO is created to purchase the item from the Vendor and have it shipped directly to the customer. The instructions below include generating the PO and a product receipt. These steps may not be required in the exam but are included for reference.
1. Go to Navigation pane > Modules All sales orders.
2. Select New.
3. Search for and select sales order number
4. On the Action Pane, select Sales order, then select Direct delivery. The Create delivery page lists all the open sales order lines as copied from the sales order.
5. Select the sales order line for the product named Projector Television.
6. The Vendor account field will be populated. A message informs you that the purchase order has now been created.
7. Expand the Line details section.
8. Select the Delivery tab and verify that the Direct delivery field is set to Yes.
9. On the Action Pane, select General.
10. Select Related orders.
11. Select the link in the Purchase order field.
12. Expand the Line details section and select the Address tab.
* The delivery address for this purchase order line is the customer's delivery address and not your company's address.
13. Select the Delivery tab.
Like the sales order line, the associated purchase order line type is also set to Direct delivery.
14. On the Action Pane, select Purchase
15. Select Confirmation.
16. Select OK.
17. On the Action Pane, select Receive
18. Select Product receipt.
19. In the Product receipt field, type a value.
20. Select OK.
21. On the Action Pane, select General
22. Select Related orders and highlight the desired record.
* After the purchase order has been updated as received, or in other words, after the vendor has shipped the goods to your customer's address, the status of the originating sales order is automatically updated to Delivered.
* The sales order can now be invoiced.
23. Select OK.
24. Close the page.
25. Select OK. Close the pages and return to the home page.
Reference:
https://docs.microsoft.com/en-us/dynamics365/supply-chain/sales-marketing/direct-deliveries

Reference:
https://docs.microsoft.com/en-us/dynamics365/supply-chain/master-planning/planning-optimization/planning-op

Explanation
Add items to an operation
To add items to an operation, follow these steps.
1. Go to Inventory management > Periodic tasks > Quality management > Non conformances.
2. In the list, select the nonconformance that you want to update.
Note: You can add or update operations only for nonconformances that are approved.
3. On the Action Pane, select Related operations.
4. On the Related operations page, select the operation that you want to add items to.
5. On the Action Pane, select Items.
6. On the Related operations page, on the Action pane, select New to add a row to the grid. Then set the following fields for new row:
Item number - Select the product that will be consumed as part of the selected operation.
Quantity - Enter the number of items that will be consumed.
7. Repeat the previous step for each additional item that you must add.
8. Close the pages.
Reference:
https://docs.microsoft.com/en-us/dynamics365/supply-chain/inventory/tasks/create-process-non-conformance