After several beta releases, Unreal Engine 4.19 is finally here. This release includes a new raft of graphical features, a new dynamic resolution feature that should help PS4 and 
XBox One developers scale across devices, a unified AR API that works on both Apple and Google devices, a new AR game template, a Maya and Motionbuilder live link plugin, sequencer improvements, improved landscape LOD, material layers and much much more.
Details from the release announcement:
Whether you are creating games, linear media, architectural visualizations, or product design tools, Unreal Engine 4.19 enables you to know exactly what the finished product will look like every step of the way. The new Live Link plugin seamlessly blends workflows between external content creation tools and Unreal Engine so you can see updates as you make changes to source content. And with the continued improvements to Sequencer, you can be the director with even more control of your scenes in real time.
When it comes to bringing the worlds in your imagination to life, the sky’s the limit. Create breathtaking vistas in large, open worlds thanks to Landscape rendering optimizations. With the new Dynamic Resolution feature that adjusts the resolution as needed to achieve desired frame rates, those worlds will run smoother than ever before on PlayStation 4 and Xbox One.
It wouldn’t be a complete release without a mountain of workflow and usability improvements, and Unreal Engine 4.19 does not disappoint in this respect. Working with Material layers and parameters is easier and more intuitive. Features for debugging Blueprints are more powerful with the ability to step over, step into, and step out. You can now save content folders as favorites. Animation tools have been improved with pinnable commands, ability to have multiple viewports, and lots more.
As always, the newest version is available for download in the Epic Game Launcher.
Be sure to read the release notes for comprehensive details of this release.