You cannot. When you start a new paragraph that paragraph will be in the style designated for following style (usually the same style) plus any direct formatting (such a a font) applied at the end of the old paragraph.

You could designate the following style to be something with a different font.

You could assign your different editors different styles with different fonts and attach that to a keyboard shortcut.

You could turn on track changes. (This is sort of what it is for.)