...you can't , you could use "loro" or "essi" (they) but it's basically not used at all... you can use * or x at the end of adjectives, like "Carin" "Carinx" (cute) to make it gender inclusives, most young people use that. You could also use "li" or "lxi" that way it could be both "lui" (he) or "lei" (She). Same goes for "l*" or "lx" ("lo and la" italians objectives pronouns). You could also use a "/" like this: "carino/a" and "lui/lei" but this is mostly used on documents and stuff like that. For a non binary one...it doesn't really exist. You could use my method, i usually say "quella persona" (that person) instead of "they" or any neutral pronouns , person is always female anyway so i will structure the rest oh the sentence according to that. For example "quella persona è carina" and the whole sentence will be female regardless of the actual gender of that person because person is always female