You can use the formula below in the Calculated Fields to calculate the line item total price after discounts:

{{ line_items.total_price }} - {{ line_items.discount_allocations.total_amount }}

• The line_items.total_price field is the line item's unit price multiplied by the ordered quantity.
• The  line_items.discount_allocations.total_amount field gives the total discount amount at the line item level. 

To get the line item's unit price after discounts, simply divide it by the quantity:

({{ line_items.total_price }} - {{ line_items.discount_allocations.total_amount }}) / {{ line_items.quantity }}