Hello @xbmbmx and welcome! I have renamed your topic to “How to style headings like text?”, don’t hesitate to read How to post in the Questions category, as
As for your question, the show rule on heading still returns a heading
element, which is styled bold by default and has a bigger font size.
It is indeed confusing at first, because you would expect the show rule function format to “replace” the element. From the docs
Note that it is written “defines how to format an element” instead of “replaces the element with the function output”.
You can understand it as doing the following:
#show heading: it => "Lorem Ipsum"
= Title
#heading[Title]
#heading(depth: 1, body: [Title])
#heading(depth: 1, body: "Lorem Ipsum")
Finally, you can make it look like text if you set it like this
#show heading: set text(11pt, weight: "regular")