An example Program.cs for Umbraco v9 project with usings refactored to a global file.

Program.cs

namespace DotNet6Umbraco
{
    public class Program
    {
        public static void Main(string[] args)
            => CreateHostBuilder(args)
                .Build()
                .Run();

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureLogging(x => x.ClearProviders())
                .ConfigureWebHostDefaults(webBuilder => webBuilder.UseStartup<Startup>());
    }
}