I have 4 examples of different stories i made with different audiences in mind. Sometimes readers overlap but is not always the case. There are always some readers that may be outside this audience, but the ones shared here are the most prominent ones.
1-Rocky the Rock is a shonen parody about an inanimate rock being an overpowered shonen protagonist.
It appeals to people who love anime and people who love absurd humor, the demographic on this one is peripheric, because it is enjoyed by people around 13-40 years old, as long as they share these interests.
2-Superduperdoopyclub is a lighthearted surreal comedic slice of life about a weird club that may or may not be a cult.
The simplistic art style and surreal lighthearted tone appeals to kids, but also to some adults.
3-Legends of Camelot: is a subversive retelling of King Arthur's story with a more detailed art style. (had to hire an artist and a colorist for this one).
It appeals to people who love medieval fantasy stories or games, and people who prefer a more occidental art style.
4-The princess villainess stares at a blank wall and does absolutely started as an inner joke about the latest Tapas trend
of overly descriptive names involving royalty and villainesses.
It appeals to people who love absurd humor and people who are part of this inner joke in Tapas.
The content defines the demographic, not the other way around....so who is your audience will depend a lot of the kind of content you want to create.
as a general rule, complex stories will appeal to older audiences and simpler ones will appeal to younger readers.
Some stories may be too dark for younger audiences, but there's always some people who are looking for edgier stuff.
Lighthearted stories also have a strong audience, sometimes people just want a good laugh or some form of escapism
Make a story you enjoy, so you can have the drive to work on it.