I have Docker Desktop running on Windows, but now would like to enable the WSL2 functionality. I enabled support for experimental features, but the WSL2 checkbox is greyed out. Windows subsystem for Linux is installed, as are all necessary Hyper-V features.
I believe that means that you are using WSL 2. To verify, check the Resources, WSL Integration tab. If it allows you to select a default WSL 2 distro, you are using WSL 2.