"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
Apple's Upcoming 6.5-Inch OLED 'iPhone X Plus' to Support iPad-Style Landscape Mode
As with Apple's plus-sized iPhones, the extra screen real estate of the larger 6.5-inch device will enable an iPad-style landscape mode that offers up more available information in apps like Mail, Contacts, Calendar, and Stocks when viewed in landscape orientation.
This has been confirmed in data gathered by Brazilian site iHelpBR from the most recent beta versions of iOS 12 and Xcode. The site forced the iOS Simulator tool to run at a resolution of 2688 x 1242 with a PPI of 458 and found that many native apps have been adapted with landscape mode features appropriate for a larger device.
In screenshots, the Contacts and Calendar apps, for example, both feature iPad-style layouts that are currently used in plus-sized devices like the iPhone 6 Plus, iPhone 7 Plus, and iPhone 8 Plus.
This suggests that Apple plans to treat the "iPhone X Plus" as it does the other larger-screened Plus devices, taking full advantage of the extra display area, and it also confirms that the upcoming device is likely to use the rumored 2688 x 1242 resolution.
Apple first introduced the new landscape mode features in iOS 8 alongside the release of the iPhone 6 Plus, the first larger-screened Plus sized device that Apple launched. Since then, the feature has been limited to the larger iPhone models.
Though the iPhone X's 5.8-inch display is bigger diagonally than the 5.5-inch display of the iPhone 8 Plus and prior plus-sized iPhones, it did not adopt the iPad-like landscape mode features.