To include a custom total row in pdf, we need to enter the details of the custom row which we need to show in sales/pdf.xml.
For example: Giftwrapping amount will not show in the Invoice Print PDF. To show the Giftwrapping amount in PDF, add the below code
in pdf.xml. Copy the pdf.xml (vendor/magento/module-sales/etc/pdf.xml)
from the vendor and put ...