How to Design a Documentation for an iPhone X, Xr, Xs, and XsMax in landscape mode.

Prior to Strategy 2019 Update 2, a document designed for a standard iPhone, such as an iPhone 8, was constrained to the "safe area" for iPhone models with rounded corners. Abiding by this safe area, meaning the area on a device that will not be covered by navigation bards, tab bars, toolbars, or other views, is recommended by Apple. For more information, see Apple's Human Interface Guidelines.
However, using documents with a safe area for an iPhone 8 appears differently on a larger iPhone, like the iPhone X. Particularly when the phones are in landscape mode, the view becomes hindered by black bars at the side with the inability to customize their colors.

iPhone 8

iPhone X

Beginning in Strategy 2019 Update 2, you can now improve the look and feel of a document on newer iPhone models. If you have an older document you want to view on a newer iPhone, you can customize the color of the side bars that appear on the screen. For instructions, see How to Modify Documents Created for Older iPhone Models. For optimal viewing, though, it's recommended to create a new document for new iPhones.

How to Create a Landscape Document for Newer iPhone Models

• In Design Mode, go to Tools > Manage Views.
• Copy a new view for a new iPhone model.
• Modify the resolution to 2436 x 1125 pixels.
  

• Click OK.
• Save your changes and run the document on an iPhone. The new view is optimized for your screen size.
  

If you are to use this approach, there are a few things to consider:

• This view is not scaled to fir the screen's safe area. You need to ensure there is enough margin space on the left and bottom so there is no view overlap with the home indicator or other physical sensors.
• This view can be used for an iPhone Xr, Xs, and XsMax because they have roughly the same aspect ratio.

 How to Modify a Landscape Documents Created for Older iPhone Models

• In Design Mode, go to Tools > Document Properties > Color and Borders.
• Change the Fill color to the content theme.
  

• Click Apply.
• Save the document.
• Run the document on an iPhone X and the layout fill color is applied to the side bars.
  

If you are to use this approach, there are a few things to consider:

• If your document has multiple layouts, apply the color change to each layout separately.
• Do not right-click on an empty space in your canvas and open the Properties and Formatting window. This changes the Body section of your document, not the sides. 
• If you want to apply the color white to your side bars, follow the steps below:
  
1. In Design Mode, go to Tools > Document Properties > Color and Borders.
2. Change the Fill color to any color other than white.
3. Click Apply.
4. Reopen Tools > Document Properties > Color and Borders.
5. Change the Fill color to white.
6. Click Apply.
7. Save the document.

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