OS Details

Apple iPhone XS Max has been launched in September 2018.
Apple iPhone XS Max have iOS 12

Screen Dimensions

Apple iPhone XS Max screen size is 6.5 inch with ~ 84.4% body ratio of actual device size. Physical dimensions for Apple iPhone XS Max device is 6.20 x 3.05 x 0.30 INCH or ( 157.5 x 77.4 x 7.7 MM).

Displaying of Units are in this order "Height x Width x Thickness"

Screen Pixel Density and CSS Pixel Ratio

"Pixel" is smallest unit/element of any display.

The total number of pixels that fit into an inch is referred to as "Screen Density" or "Pixel Density" and it measured as "Pixels Per Inch".
Pixel Desnsity have limits to display Pixels Per Inch depends on different screen sizes. When number of pixels per inch increases than it's screen-size limit, the Display resolution will increase but actual device width/height in pixels remain same. Actual device pixels are known as Device Independent Pixels or CSS Pixel Ratio.

Apple iPhone XS Max resolution is 1242 x 2688 ^PX with ~ 458 pixel desnsity.
Apple iPhone XS Max viewport size is 414 x 896 ^PX with ~ 153 actual pixel density, which means it have 3 xxhdpi display pixel density.

Screen Resolution and Viewport

The sum of pixels which are displaying on a device is called as "Screen Resolution". and sum of actual pixels of any device is reffered to as "Viewport".

Apple iPhone XS Max have 6.5" physical screen size and its resolution is about 1242 x 2688 Pixels with approximately 458 PPI pixel density. Apple iPhone XS Max has viewport size 414 x 896 Pixels and its pixel ratio is about 3.

For better understanding screen actual sizes, viewport sizes, display resolution and about their density click here.

CSS Media Queries

Apple iPhone XS Max Media Queries (In terms of Mobile only)

@media only screen and (min-width: 414px) and (max-width: 767px) { /* Your Styles... */ }

Apple iPhone XS Max Min-Width Media Queries

@media only screen and (min-width: 414px) { /* Your Styles... */ }

Apple iPhone XS Max Min-Height Media Queries

@media only screen and (min-height: 896px) { /* Your Styles... */ }

Apple iPhone XS Max Landscape Media Queries

@media only screen and (min-width: 896px) and (orientation: landscape) { /* Your Styles... */ }

Apple iPhone XS Max Portrait Media Queries

@media only screen and (min-width: 414px) and (orientation: portrait) { /* Your Styles... */ }

Apple iPhone XS Max Retina Media Queries

@media
  only screen and (-webkit-min-device-pixel-ratio: 3),
  only screen and (   min--moz-device-pixel-ratio: 3),
  only screen and (     -o-min-device-pixel-ratio: 3/1),
  only screen and (        min-device-pixel-ratio: 3),
  only screen and (                min-resolution: 458dpi),
  only screen and (                min-resolution: 3dppx) { 
    /* Retina styles here */
}
                                

Retina is actually based upon device pixel ratio. Devices mostly have 2x or 3x display so you can use general retina media queries to display high resolution content on all kind of devices. Retina 2x and Retina 3x media queries given below:

Retina 2x Media Query

@media
  only screen and (-webkit-min-device-pixel-ratio: 2),
  only screen and (   min--moz-device-pixel-ratio: 2),
  only screen and (     -o-min-device-pixel-ratio: 2/1),
  only screen and (        min-device-pixel-ratio: 2),
  only screen and (                min-resolution: 192dpi),
  only screen and (                min-resolution: 2dppx) { 
    /* Retina styles here */
}
                                

Retina 3x Media Query

@media
  only screen and (-webkit-min-device-pixel-ratio: 3),
  only screen and (   min--moz-device-pixel-ratio: 3),
  only screen and (     -o-min-device-pixel-ratio: 3/1),
  only screen and (        min-device-pixel-ratio: 3),
  only screen and (                min-resolution: 384dpi),
  only screen and (                min-resolution: 3dppx) { 
    /* Retina styles here */
}
                                

Apple iPhone XS Max Specifications

• Launch Date September 2018
• iOS 12
• Physical Screen Size 6.5 INCH
• Resolution 1242 x 2688 PX
• Viewport Size 414 x 896 PX
• Pixel Density 458 PPI
• Device-Independent Pixels 153 PPI
• Pixel Ratio 3 xxhdpi
• Width 1242 PX
• Height 2688 PX
• Device Width 414 PX
• Device Height 896 PX
• Dimensions 157.5 x 77.4 x 7.7 mm (6.20 x 3.05 x 0.30 in)
• Weight 208 g - 7.34 oz