Hi Emily, my name is Neil and I'm a Windows 11 user like you.
Sorry you're having difficulty pairing your Sony headphones.
Have you tried wiping your headphones pairing memory?
To do this, Disconnect the micro-USB cable, turn OFF the headset, then press and hold the Power button and the Play/Pause button simultaneously for more than 7 seconds.
The blue indicator flashes 4 times, and the settings such as the volume adjustment are reset to the factory settings. This operation deletes all pairing information.
Once you have done this, on your computer, go to Start > Settings > Bluetooth & devices and delete any pairing information for your headphones here too. Leave this settings page open.
After doing this, it's like both your headphones and your computer have never been paired previously.
Starting again, make sure your headphones are within 1 metre (3 feet) of your computer, ready for pairing. Since you have wiped the memory of the headset, your headphones should enter pairing mode automatically when you power them on. If they do not, go back and follow the previous instructions to reset your headphones to factory settings.
Once in pairing mode, the indicator flashes blue and red alternately and you should hear a voice guidance say “BLUETOOTH pairing”.
Going back to your computer, your should still be on the Start > Settings > Bluetooth & devices page. Click on "Add device".
Select "Bluetooth" in the pop up box.
Look for your headphones in the list.
You want to pair with "WH-CH700N" (do not pair with anything LE).
If you're asked for a pin number, type: 0000 (that's four zeros)
When your headphones and computer are paired with each other and connected, you will hear a voice guidance "BLUETOOTH connected".
If you don't see "WH-CH700N" on your computer. Go back to "Add device" and this time choose "Everything else".
Let me know how you get on.
Kindest regards,
Neil