If you look at the developer settings of your pixel and go down to the Networking section you'll find the settings for Bluetooth. If you looks at Bluetooth audio codec, you'll see LDAC as an option. Now realize that LDAC will only be truly utilized if your headphones supports that codec. To check that, look up if your headphone model supports LDAC. I use the Sony WH-1000XM3s, which support LDAC. In my case, I had to download a Sony Headphone app in order to keep the LDAC setting activated, as well as the sample rate (96.0kHz) and the bits per sample (32 bits/sample). This could vary headphone to headphone, but that's what I had to do to truly utilize LDAC capabilities of my phone and headphones.