Create-react-app: Experimental syntax 'classProperties' isn't currently enabled

I am using create-react-app and don't want to eject. Is there any-other way to fix this?

   class SlidingUpPanel extends React.Component {
   static propTypes = {
               ^
   visible: PropTypes.bool,
   height: PropTypes.number,   draggableRange: PropTypes.shape({

Add @babel/plugin-proposal-class-properties (https://git.io/vb4SL) to the 'plugins' section of your Babel config to enable transformation.

Installed @babel/plugin-proposal-class-properties already! But how to fix this without ejecting?