One of the stupid activity/sport faces has a digital seconds display. I wish there were a better one. I think Modular + digital seconds complication is probably the closest, but it doesn’t give HH:mm:ss like it should.
You can add digital or analog seconds to most of the faces that accept complications. I use the Solar face with the analog seconds view, which is larger than the complications.
I hope they add a hh:mm:ss watch face/option soon.