KOMA scripts: scrartcl: How to change the font color of the page number

You can use addtokomafont{pagenumber}{...} to your advantage. Assuming you want a red page number, you can use it as shown in the following example:

documentclass{scrartcl}
usepackage{pdfpages}
usepackage{geometry}
usepackage[automark,headsepline,footsepline]{scrlayer-scrpage}
usepackage{xcolor}
addtokomafont{pagenumber}{color{red}}
begin{document}
CHECK PAGENUMBER FONT
end{document}