Upscale is a new jailbreak tweak that lets you run your iPhone 5s, iPhone 5c, or iPhone 5 at iPhone 6 or iPhone 6 Plus resolution. The older 4-inch devices run at a resolution of 640 x 1136 pixels, and the tweak lets you change this to any arbitrary value.
Jailbreak Apps and Tweaks
HandyKey Jailbreak Tweak brings back 4-inch keyboard to iPhone 6 and iPhone 6 Plus for easier one-handed use
With the release of the 5.5-inch iPhone 6 Plus, Apple added some iPad functionality to the iPhone by enabling landscape mode on the home screen and in many apps. Just like on the iPad, apps in landscape mode on the iPhone 6 Plus run in the split mode, usually with a list on the left, and a detail view on the right.
UntetheredHeySiri: Jailbreak tweak lets you use ‘Hey Siri’ hands-free activation without being plugged in
Apple added a really useful feature to Siri, that lets you activate it hands-free just by saying “Hey Siri.” The feature sadly works only when your device is plugged in.
The iPhone 6 and iPhone 6 Plus come with larger, higher resolution displays that give apps additional real estate to show more content, images, text and so on. Developers, however, need to update their apps to take advantage of the larger screen. Unoptimised apps run in scaled mode, where everything looks much larger than it should be.