No, there is no official Figma file for the default theme. An official Figma file is only available for the Hyvä UI Library.
However, a community-contributed Figma file based on an older version of the default theme is publicly available (courtesy of Kristaps Rjabovs from Magebit).
Please note: This file is not up-to-date with recent theme changes and is desktop-only, lacking responsive behavior.