Is it possible to do this with CSS code?

I would like to add markers such as \\ (i.e.:\\some text\\) that would format “some text” in any way I want via CSS code?

By that, I mean being able to format text in the middle of the text of a rem (otherwise I would use tags). In the same way we can underline or italicize a portion of a text, I would like to create a specific format for a portion of a text.