sudo apt-get update && sudo apt-get install dotnet-runtime-6.0 dotnet-sdk-6.0
You need the dotnet-runtime package to run .NET applications and dotnet-sdk package to develop .NET applications. Fedora uses a similar naming convention for its packages
https://packages.fedoraproject.org/pkgs/dotnet6.0/ . It would be awesome to see these packages in Debian one day.