Freedom at the control center
In the past, Bluetooth could only be switched on the "Settings" screen, but since iOS 13, it can be switched immediately in the "Control Center".
Make sure both devices are powered on and ready to connect to Bluetooth. Next, display the Control Center and press and hold the Bluetooth icon in the upper left box. Tap "Bluetooth".
▲ Select the device you want to connect. If both are "connected," tap the one you want to disconnect (left). The selected device is in the "connected" state, and the others are "not connected" (right)
By the way, if you tap "Bluetooth settings …" displayed in the control center, it will automatically switch to "Bluetooth" in "Settings" and you can check details of connected devices.
Wi-Fi can be easily switched
Wi-Fi can be switched in the same way. Display the Control Center and press and hold the Wi-Fi icon. Tap "Wi-Fi" and select the Wi-Fi you want to connect to.