class classA extends Component {

  componentDidMount() {
     new Expand(this.expand)
  }

  render(){

    return(
      <SomeComponent1 className={style.container} innerRef={e => this.expand= e}/>
    )
  }
}

class SomeComponent1 extends React.Component {
    render() {
       return <div ref={this.props.innerRef}>Hello</div>
    }
}