useImperativeHandle

const FancyInput = forwardRef(function FancyInput(props, ref) {
  const inputRef = useRef(null);
  useImperativeHandle(ref, () => ({
    focus: () => inputRef.current.focus(),
    clear: () => { inputRef.current.value = ''; },
  }));
  return <input ref={inputRef} />;
});

function Parent() {
  const ref = useRef();
  return (
    <>
      <FancyInput ref={ref} />
      <button onClick={() => ref.current.clear()}>Clear</button>
    </>
  );
}