This video explains the basics of sending QGIS maps to a printing press. It explains the differences between RGB and CMYK colors, and gives step-by-step instructions for several methods of converting images, PDFs, and SVGs using a range of software options.
ICC profiles - WIndows
https://www.adobe.com/support/downloads/iccprofiles/icc_eula_win_end.html
ICC profiles - Mac
https://adobe-icc-profiles.apponic.com/mac/download/
Inkscape/Scribus Guide
https://www.klaasnotfound.com/2016/06/05/creating-cmyk-prepress-pdfs-with-inkscape-and-scribus/