When playing any King game, you can turn the sound of the game on or off in the app. When entering the game, tap the cogwheel icon to open the menu. You will find two sound options.
One is a musical note, which controls the in-game music. The other option is a speaker icon, which controls sound effects in the game. Tap them to switch the sounds on or off.
After these two options are enabled, you can then use the volume up and down buttons on the side of your device to control the volume level to your comfort.
If you notice both of these are on but you are still not hearing sounds in-game, please test other apps or media on your device, as it may be a system or hardware issue.