Apple still has plenty left in store for iOS 13 before moving on to iOS 14 (which we will likely hear about this summer at WWDC). A week after the release of iOS and iPadOS 13.3.1, it began beta-testing iOS 13.4. This point release brings several welcome new features.
Update 02/19/20: Apple has released the second beta version of iOS 13.4. See instructions below for how to register your device to participate in the public beta.