The sdk has everything, and there are two runtimes for Linux. Asp.net core and .net runtime. The desktop runtime is windows only.
If you want to build an app, then install the sdk, if you just want to run a console app, install .net runtime for Linux.
Note: 3.1 is nearing end of life, you should use .net 6
the docs say its:
sudo yum install dotnet-runtime-3.1
Will .net6 run on Visual Studio 2019? What's the difference between Community and Professional Editions? It seems like .net6 runs only with VS 2022?