I have sound using Bluetooth only

Start here:

If you hear no sound or distorted sound from your iPhone, iPad, or iPod touch speaker - Apple Support

The iPad User Guide is a rich source of information about your iPad. If you are experiencing difficulties with sound, here is a direct link to the relevant section of the Guide:

Adjust the volume on iPad - Apple Support

As you’ll see, you can adjust the audio volume in several different ways…

1) the physical buttons on the edge of the iPad…

2) using the Control Centre, with a downward swipe from the top-right corner of the screen - then drag 

3) or, for system sounds, dragging the slider in iPad settings:

Settings > Sounds > [Ringtone and Alerts Volume]

Also be aware that your iPad can also be silenced from the Control Centre:

If sound has not been silenced - and the relevant volume controls have been adjusted-up, try a forced restart of your iPad - as this will often clear an isolated software issue:

Force restart iPad (models with Face ID or with Touch ID in the top button)

If your iPad doesn’t have the Home button, do the following:

1. Press and quickly release the volume button nearest to the top button.
2. Press and quickly release the volume button farthest from the top button.
3. Press and hold the top button.
4. When the Apple logo appears, release the top button.

Force restart iPad (models with the Home button)

Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.

If you continue to experience difficulties, you might be well advised to seek assistance directly from from Apple Support. You can contact the Support Team using the Support link at top-right or bottom-left of this page. Alternatively, you can initiate and manage your support cases using the excellent Apple Support App. If not already installed on your iPad, the App can be downloaded from the App Store:

https://apps.apple.com/gb/app/apple-support/id1130498044

You might also visit the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP) - where the technicians will be able to test and assess your iPad:

Genius Bar Reservation and Apple Support Options - Apple

You can try to force restart your iPad. If you’re using iPad 6th Gen your iPad will have a home button. So to do this restart press and hold both the home button and the Sleep/Wake button till you see the Apple Logo on the screen. Once you see the Logo you can release the buttons and allow the iPad to continue to boot normally. If this doesn’t work, then you may have some sort of hardware issue going on with your iPad and I would suggest taking your iPad to an Apple Store Genius Bar and have them diagnose it. They will be able to assist you in the next steps.