Apple revealed this feature by showing off a refreshed Magic Keyboard for the new iPad Pro, but this will work on all iPads that support iOS 13.4 and with all mice, including Bluetooth and USB models.
Considering I just ordered the updated Smart Keyboard, I’m glad to hear I can connect a Bluetooth mouse and take advantage of the new functionality. Though, having played around with mouse support, it’s interesting that Apple’s own Magic Mouse isn’t fully supported on iPadOS 13.4. The device connects and offers basic functionality but some of the more advanced gestures don’t work unfortunately.
On a related note, as is the case with stuff like this, it’s only natural that Apple announces a new iPad Pro days after I buy the current one. That said, I’m happy with the one I have and I’m glad the new Magic Keyboard supports the previous generation Pro.