The default font used for Invoice PDF is dejavusans. The font is referenced in /public/css/invoice-pdf.css file.
@font-face {
font-family: 'dejavusans';
src: url('../../vendor/dompdf/dompdf/lib/fonts/DejaVuSans.ttf') format('truetype')
}
You can add custom font by copying your font to folder /public/fonts then add the font css to invoice-pdf.css as shown below;
@font-face {
font-family: 'custom';
src: url('./../fonts/custom.ttf') format('truetype');
}
Edit .env file and add or change value of PDF_FONT=FONT_NAME replace FONT_NAME with font real name e.g PDF_FONT=custom
You can use the same method to add custom fonts to other modules i.e credit notes, estimates etc