Download Font what you want in Google Font
wget -c https://fonts.google.com/download?family=Titillium%20Web
Create Directory For Assign Font
this is will read for only level user
mkdir -p ~/.local/share/fonts
or
This is will read for All system Linux
mkdir -p /usr/share/fonts/
Extract and copy font to directory
unzip Titillium_Web.zip -d ~/.local/share/fonts
Clear cache Fonts
fc-cache -f -v
Search font titillium to make sure font already updated
fc-list | grep -i titillium