g-docpanel.js

const { registerPlugin } = wp.plugins;
const { PluginDocumentSettingPanel } = wp.editPost;

const PANEL_NAME = 'my-panel';

const Render = () => (
	<PluginDocumentSettingPanel
		name="custom-setting-panel"
		title="Custom Panels"
		className="custom-panel"
	>
		Custom WP Gutenberg Plugin Panel Content
	</PluginDocumentSettingPanel>
);

registerPlugin( PANEL_NAME, {
	render: Render,
	icon: 'palmtree',
} );