Ah, I see.
There is...but it is a bit complicated.
Some folks trade screen space for larger text by using a lower resolution. The good thing about this technique is that everything is bigger. The bad thing is that you have less usable space, and depending on the display, it may be less crisp and focused overall.
If lower resoltions don't work, then you would have to change text size everywhere. Finder is pretty easy, but won't offer help inside applications. Apple covers the basics here.
