One feature difference between iPhone XS and iPhone XS Max is Display Zoom, an accessibility feature that makes content on the screen appear larger than the default resolution. This was introduced on iPhone 6 and iPhone 6 Plus, but was not available on the iPhone X. The display feature is still absent on iPhone XS, but the larger iPhone XS Max version restores it.
Display Zoom can be turned on in the Settings app under Display & Brightness and View. Standard shows more content on the screen, and zoomed shows larger controls for content. Display Zoom makes elements on screen more legible with larger tap targets. All modern iPhones support adjusting text size where Dynamic Text is supported.