I need to change the Invoice template

I need to customize the invoice template for a shop project.

I know this is planned as a future feature, but I need to change it now, and I’m trying to find where the invoice template actually lives.

I already tried modifying the invoice view in the views folder, but that had no effect.

To be clear: I’m not looking for the email template. I need the actual invoice layout that gets rendered into the PDF.

Can someone point me to the correct file or place in the codebase where the PDF invoice is generated?