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.
Some of the best sources are writing - specific platforms. For example, Poetry.com is a great place for poets to post their work. It focuses mainly on poetry and has a community that appreciates the art form. Storybird is another good one, especially for stories. It has a really creative interface that can inspire you while you write and share. Additionally, your own personal website can be a good source. If you have the skills to build and manage it, you can have complete freedom to present your poetry and stories in any way you like.
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.