Your Sony Bravia probably uses Apple's AirPlay 2 screen mirroring protocol.
All fairly new iPads use AirPlay 2, as well.
Are you trying you trying to AirPlay a certain app or apps?
You cannot AirPlay more than one device at a time. to another AirPlay capable device.
To AirPlay to your Sony Bravia, you need to have no other device using AirPlay on your TV
To use AirPlay on your TV to just mirror your iPad, you tap the Screen Mirroring option in the iOS swipe down Control Panel.
When you do this your AirPlay capable TV should pop-up an AirPlay code on the TV screen.
On the iPad, there should be a code box that appears where you type in the code shown on the TV to activate Airplay mirroring between your TV and your iPad.
NOW, if you are trying the AirPlay an app, this ability is ONLY available on a per app basis as the developer of the app can or cannot allow AirPlay mirroring of their app.
It is the same procedures for AirPlay-ing within an app.
A code will pop-up on the TV, you enter the code in a code box on the iPad.
You may find with many streaming video types of apps that some will allow AirPlay mirroring and some will not.
Best of Luck to You!