How to add Environment Variables in Visual Studio

Question

        private static async void InitializeSupabaseAsync()
        {
            var url = Environment.GetEnvironmentVariable("SUPABASE_URL");
            var key = Environment.GetEnvironmentVariable("SUPABASE_KEY");
            SupabaseClient = new Client(url, key, new Supabase.SupabaseOptions
            {
                AutoConnectRealtime = true
            });
            await SupabaseClient.InitializeAsync();
        }