An expert? No, some specifics in the history and architecture of stuff that only a school can teach you is required to take it to a level that makes one an expert. Become a professional without it? Yeah, there's enough online courses, education videos, and professionals sharing their tricks and tips that someone can get familiar with it to get started; then through experience and customers they can become a professional.
Understanding why something for typography is how it is, is important. Just scaling up a vector image to fit on a billboard is kinda useless, you see the billboard from below and afar, one has to understand the distance and perspective and apply this.
But yes, I think someone can get very far with just being online.