It has been observed of a feature to include the difference between iPhone XS and iPhone XS Max is Display Zoom, with an accessibility feature making the content on the screen appearing larger than the default resolution. With the introduction of iPhone 6 and iPhone 6 Plus, it was notably absent on iPhone X which displays the feature still being absent on iPhone XS, but the larger phone has a version of iPhone XS Max which can restore it.
Display Zoom is a feature which one can turn on in the Settings app under Display & Brightness and View. With the Standard being shown with more content on the screen, and zoomed showing larger controls for the content one can hence utilize Display Zoom making elements on the screen with more legibility and larger tap targets. Hence with modern iPhones supporting adjustment of text size where Dynamic Text is supported.
With the Dynamic Zoom getting presented with a dramatic difference on iPhone 6 Plus with other 5.5-inch phones, having been with a less subtle on iPhone 6 and other 4.7-inch phones. Thus with Display Zoom presenting a version of the operating system being designed for much smaller screens is what being scaled up. Hence with the effect being the same as running with an app is designed for a 4-inch phone like iPhone 5 which has a larger screen without any full resolution support.
With iPhone X and iPhone XS having a larger 5.8-inch display is with a different aspect ratio to iPhone 5 and iPhone 6 style phones. Hence with the reason being, having no smaller versions of apps can easily scale up for Display Zoom.
iPhone XS Max & iPhone XR
iPhone XS Max which has a larger 6.5-inch display with the same aspect ratio of iPhone X, however, has apps being designed for iPhone X and iPhone XS which scales up in Display Zoom on iPhone XS Max.
With this likely being the meaning one will be able to see the Display Zoom which features on iPhone XR and the features being a larger 6.1-inch display which has been with the same aspect ratio as iPhone X.
With the effects thereby of Display Zoom visually being less dramatic on iPhone XS Max, however, as there has been a difference in size being from 4-inch screens to 4.7-inch and 5.5-inch screens is hugely being dramatic than 5.8-inch screens to 6.1-inch and 6.5-inch.
Hence we come to the end by concluding the above topic courtesy taken from 9to5mac which Dynamic Zoom has a Standard Mode wherein which one can increase to Zoom Mode along with sizing and text on the home screen within apps such as Mail. There has been an advantage of Display Zoom which took iPhone 6 and iPhone 6s Plus, with making text with the interface which can be made bigger and easier for readability purposes.