Recently I bought HP Spectre x360 Convertible that has a fantastic crisp 4K screen. Using CTRL+F1 (upto F6 usually) one can access console. With 4K screens now becoming available the default font size becomes really minute and one would need to increase it somehow. gnome-terminal provides shortcut SHIFT+CTRL and plus key (+) to increase font size when needed, or profiles which can be changed. But with console something more is necessary. Font used in the console is monospaced and is not the same as the tt or otf fonts used for document and browsers. In addition, there is also a limited selection fonts and sizes to choose from. So here is how to do that. Go to a console and login. Following command has to be run as root or using sudo.
sudo dpkg-reconfigure console-setup
Leave the first two screen settings as is. On third one you will see list of Font styles as Fixed, Terminus (and its variations), VGA and few others. Fixed is the default one and at least for me its biggest font size was still small for me. So I used VGA. Terminus looks fantastic but as the warning says it is not good for programming because of the way some of characters are represented. So select VGA and move to next screen. Select the biggest font and press enter. Within few seconds change will take effect. Try other font styles and sizes to suit your need.