You can customize the settings for VoiceOver, such as the audio options, language, voice, speaking rate, and verbosity.
To increase or decrease your iPad’s volume, including the volume of VoiceOver speech and sounds, as well as all other iPad audio, press the volume buttons on iPad.
To temporarily reduce the volume of other iPad audio while VoiceOver is speaking, go to Settings Use VoiceOver gestures on iPadAccessibility features for vision on iPad