The editor and the console font size can be changed with ctrl+mouse wheel (ref), but how do you change the debug panel font size? I've been all through
Colors & Fonts and haven't been able to find a way to do this.
It's not possible to change font size only for Debug, Run etc. tabs. But you can change font for whole IDE in
File | Settings | Appearance & Behaviour | Appearance and here check
Override default fonts option and change font size.
P.S. Try to use Grep Console plugin to make logs more readable.