change fonts in a variable

Create two Character Formats, defined all As-Is or blank except for Font Family, for example:
Tagname: Webdings, Family: Webdings
Tagname: Kodzuka Gothic, Family: Kodzuka Gothic

Suppose the variable desired is the prohibited circle icon with a non-breaking space and text "STOP!"

Define your variable, named, say "Stop here"
Definition: <Webdings>x<Kodzuka Gothic>\ STOP!

There is no need to include <Default ¶ Font> at any point, because the <KG> tag completely replaces the action of the <Wd> tag and the end-of-variable turns off all Character Formats applied inside the var.

In the Unicode age, using Webdings (and codepage/overlay fonts generally) is discouraged if you have a font that populates the glyph you need. For this example, that would be
'PROHIBITED SIGN' (U+1F6C7).

If you are doing a workflow that for any reason fails to embed the Webdings font, such as to HTML, the glyph invoked may well show up as some nearly random Roman character ("x" in the case of the prohibit glyph).