not without "breaking" the install, like in this extension. I've been wanting a way to set the font family for the UI, but that's not exposed by the settings and it would require this kind of "surgery". I never liked the idea of messing with VS Code files, so I never bothered changing this.
Out of curiosity, I don't get the "blocky" complaint; what kind of layout do you have in mind? Any apps that implement it?