Support small text (<small>) in writer field

Is there a way to insert small text (i. e. text within <small></small> elements) in a writer field? HTML entered in that field appears to be converted to plain text and there doesn’t seem to be any Markdown syntax for this.

In Kirby 4 you can add custom marks/nodes to the writer field: Writer marks/nodes | Kirby CMS

Yeah, but I’m using Kirby 3 for reasons. But it turns out I need a more complex set-up because there can be multiple paragraphs of small text, so I’m probably going to create a custom block for that.