I want to customize the content of the invoice PDF(printable from admin backend).
But all the threads I read so far (Magento devdocs do not contain guidance on this) direct to folders like
model/order/PDF/invoice.php that simply do not exist anymore in Mangento 2.3.3.
Please help me to find out where the PDF related
*.php files are now in Magento 2.3.3.