Apple x's mobile phone text message voice is very low.

This is because your iPhone X has turned on the gaze sensing function, which can be changed to the same loud sound.

When a mobile phone is talking, if you pick up the screen of the mobile phone or just use the mobile phone, iPhone X is detecting whether the eyes are looking directly at the screen through facial recognition, thus automatically adjusting the volume. IPhone X will automatically turn down the sound gradually. This function can be turned off.