Drop caps in Para Styles is limited to the number of characters, not to words. But it would be a good idea for a feature request. Can you submit it?
Imagine you want to have drop caps on the first word of each para styled "Style xxx". A simple grep does it:
Search the format: Style xxx
Replace the format: Word-DropCaps_CharStyle
Word-DropCaps_CharStyle is your char style that simulates the "word" drop caps size and offset.
~C is the anchored block that simulates the place of the "word" drop caps.
Thank you for those articulate answers! Yes, I would love to suggest this to Adobe, though I doubt I'd ever employ it stylistically (cap overload). It was a question a student asked me and I didn't have a good enough answer, so I thought I'd extend the question to the community. Greps are a little too advanced for my beginners, but it's nice to know it's possible. Thanks again, all. I'm sure I will turn to you again ; )