My original tumblr post was here. Sourced on tumblr to Northern Man, who identifies the figure as The Great Harlot of Babylon. In the context of the film, it is the Maschinenmensch in Metropolis, played by the actress Brigitte Helm (1906-1996).
Tumblr favorite #1908: The Great Harlot of Metropolis
Appears to be a production still, not an actual frame-grab from the movie.
I think you’re probably right, although sometimes with Metropolis it can be hard to tell, given that there’s still (!) missing footage and who knows what’s floating around out there, and in what condition.