Playing CoD Mobile on a smartphone with virtual controls is not very convenient. Because you need to run, aim and shoot at the same time. It is much easier to fight with a mobile controller because hardware controls are just simply easier to use than touchscreens for an FPS.
Activision You can use a controller to play CoD Mobile via Bluetooth. Open the Settings app on your phone, and select Bluetooth. Hold down the PS & Share button on your PlayStation controller, or the Connect button on your Xbox controller.