Need a paragraph style that doesn't override a font style within

When I set up a Paragraph style and apply it to Placed text, most of the time the Paragraph style will honor any embedded style anomalies (such as a single word in a paragraph that is italic rather than regular text). But sometimes a Paragraph style will turn all text within a paragraph to a single style (regular).

I know that if I create an "italic" Character style and apply that to every word in a book that arrives in italic, a Paragraph style will honor those. But is there any way to choose "No style" when setting up a Paragraph style so the Placed text remains stylistically intact when it arrives? I don't see that option - only regular, italic, etc, which will apply to the whole paragraph.

I can't explain why the italics within paragraphs sometimes survive my Paragraph styles and sometimes don't - I doubt some of my clients are marking their Word docs in any special way and others aren't - I doubt any of them are.

Please let there be a benevolent Adobe-Deity out there that won't make me mark every single italic word in every book.

I'm running Adobe 20.0.1 on a MacBook Pro, Sequoia 15.2.