you use the singular they Subject/Object/Possessive adjective/Possessive pronoun /Reflexive and it'll look it up in the internal Pronoun Database to figure out which pronoun set that person uses, and it'll match it.
It also notices how you capitalize it, and matches it.
So "WHAT THE HELL IS {THEY}DOING HERE?" will correctly render as "WHAT THE HELL IS SHE DOING HERE?"
It's simplistic and doesn't handle the way people tend to actually use plural they/them pronouns, but it works.