As explained by this page on Wikipedia, it's called a section break. I point you to the text of the annotation on the right side of the page where it pairs this term with the same kind of glyph you posted:
Open pages of the book Alice's Adventures in Wonderland, showing an ornate section break on the lower left page created from asterisks. It is used to signal a pause for the reader and a transition in the narrative.
And also the section on flourished section breaks:
Space between paragraphs in a section break is sometimes accompanied by an asterism (either proper ⁂ or manual * * *), a horizontal rule, fleurons, or other ornamental symbols. An ornamental symbol used as section break does not have a generally accepted name. Such a typographic device can be specifically referred to as dinkus, space break symbol, paragraph separator, paragraph divider, horizontal divider, thought break, or as an instance of filigree or flourish. Ornamental section breaks can be created using glyphs, rows of lozenges, dingbats, or other miscellaneous symbols. Fonts such as Webdings and Wingdings include many such glyphs.
In HTML, horizontal rules can be generated using the hr tag, which
generates a paragraph-level thematic break. For more ornate
presentation, CSS can be used to replace the line with an image.
As you've rightly acknowledged, the form a section break takes is entirely up to the person creating the publication.