You can try posting them on popular writing platforms like Wattpad or Archive of Our Own. These sites have a large user base and are known for hosting various types of stories, including horror.
I think posting on dedicated comic forums or communities such as DeviantArt can be a good start. They often have passionate comic lovers who are eager to discover new works. You might also consider pitching to established comic publishers' online platforms if you aim for a more professional reach.
Well, some good options are literary magazines or websites dedicated to short fiction. For example, 'The New Yorker' or 'Electric Literature'. These often have a more curated and discerning audience. But it can be competitive to get published there. Another option is to start your own blog or website to showcase your work and build your own readership over time.