Dynamically read connection string in ASP .NET Core

Startup.cs

        public IConfigurationRoot ConfigurationRoot { get; set; }
        public static string ConnectionString { get; private set; }
      
        public Startup(IConfiguration config,IWebHostEnvironment env)
        {

            ConfigurationRoot = new ConfigurationBuilder()
                .SetBasePath(env.ContentRootPath)
                .AddJsonFile("appSettings.json")
                .Build();
        }