Are there not any futanari characters yet?
With the option turned on, I've only seen Alexa as a femboy so far.
Futanari have both male and female genitals. It's in its definition. In Japanese, futa means "two" and nari means "figure," which refers to such a person's perceived dual nature.
If a character only has male genitals with no female genitals and looks feminine, then they're either a femboy (girly appearance) or a shemale (womanly appearance).