How to use multiple physical keyboard layouts on Android Oreo 8.1.0 Go Edition phones?

After connecting Bluetooth keyboard to my Android phone, I can't add more than one physical keyboard layout. Here is the picture I mean, using the Ctrl + Space shortcut that has multiple physical keyboard layout options, I can't. My Android phone version is 8.1.0 Oreo Go Edition. I can't even use the Android system keyboard shortcut! Example: Notification is displayed by pressing search + n. But pressing the shortcut key is not working. Here is the picture