Basically, I want to create one page to host my comics, but I want for buyers to purchase them separately rather than as a bundle. Is this possible? or do I have to make a page for each release?

No matter how this is called, Itch does lack that feature. For games the common name is dlc. Separate items you can purchase, that share a project.

There are some special cases that can be done with the existing options, but they lack some flexibility. There is a feature called individually priced files. But this is not what it sounds like. It is not payment per file, it is unlocking tiers per highest payment. And you can't increase tiers with additional payments.

So, yes, every item you want to be available individually, you must make a project page. You can bundle those pages together with an Itch-bundle.