Kestrel and OpenSSL cipher suites
Cipher suite selection and TLS version configuration is not yet implemented. Check this issue on GH: https://github.com/aspnet/KestrelHttpServer/issues/1865
Since kestrel is edge-ready it will probably have configuration for this in the future. Most importantly they want a streamlined, aka for all OS the same, configuration API.
It seems like it solved in ASP.NET Core 3.0, you can see it under "CipherSuitesPolicy"https://docs.microsoft.com/en-us/aspnet/core/fundamentals/servers/kestrel?view=aspnetcore-3.0