During your service, you're pretty much allowed to do whatever you want that will benefit your community. Your post and the program you'll be working under with have a framework approved by the host gov't and PC HQ. You'll be receiving tons of training on your primary assignment, ie that framework, as well as minor training on how to do projects outside the framework.
Anything you do outside that framework is a secondary project or secondary work. And yes, you can do those kinds of things. If you're an agriculture volunteer and you want to start a grass roots comics campaign, go right ahead.
Sometimes secondary projects and initiatives fall into your lap, come from Post staff, but usually you've got to hunt down these things in your community, or find a way to generate interest in them.
In the end, you can do whatever projects you wish. So long as you're helping your community!