Take Apple XS MAX as an example, and use the imovie clip app that comes with Apple's mobile phone. The operation steps are as follows:

1. Find and open the imovie clip application; In the mobile phone;

2. After opening, in the project bar at the top of the screen, click Create Project;

3. Select the video type as required. You can choose to create a movie as a trailer, and click Create Movie;

4. After creating the video type, select the video to be modified in the media bar;

5. Find and click the video to be modified, and then click Create Movie at the bottom of the screen;

6. Click the Create Movie page and go directly to the Edit Movie page;

7. Rotate the video position with two fingers, and a rotating arrow will appear. Change the video from portrait screen to landscape screen as needed, and click Finish;

8. Click Play Video after saving, and you can see that the video has been designed from portrait screen to landscape screen, and it will be played on TV accordingly.