```ts
// MyComponent.stories.ts

import { Story, Meta } from '@storybook/angular/types-6-0';
import { INITIAL_VIEWPORTS } from '@storybook/addon-viewport';

import MyComponent from './MyComponent.component';

export default {
  title: 'Stories',
  component: MyComponent, 
  parameters: {
    //👇 The viewports object from the Essentials addon
    viewport: {
      /👇 The viewports you want to use
      viewports: INITIAL_VIEWPORTS,

      //👇 Your own default viewport
      defaultViewport: 'iphone6',
    }
  },
} as Meta;

export const myStory: Story<MyComponent> = () => ({
  template: '<div></div>'
});
myStory.parameters = {
  viewport: {
    defaultViewport: 'iphonex'
  }
};
```