You must have heard that Ionic Framework has released Ionic 5 which has many new features and performance upgrades. According to Ionic Framework officials, Ionic 5 is 2X faster than Ionic 4, it has lots of design related improvements specially for latest version of iOS like Dark Mode, Segment, Header, Large Title, Small Title, Swipe to Close Modal, brand new Icons and Animations.
Here you can see the complete list of new features of Ionic 5. If you are planning to migrate from Ionic 4 to 5, you should read this before you move forward. For easiest and complete migration guide, please read this article.