I have been working Flutter app with .NET Core web API to connect the database. Now I have a question about a Web API.

In my backend activity through web API, I need to call an external API endpoint to make some changes in the external app and I’m using .net core web API also enabled swagger and i will implemented below code and tested it not calling external Api and nothing changed in external app Client Side

This is my code

    namespace test.Controllers
{
   
    public class testController : ControllerBase
    {
        private ItestService _tstService;
        public TestController(ItestService tstService)
        {
            _tstService = tstsService;
        }
        [HttpPost]
        [Produces("application/json")]
        [ProducesResponseType(200, Type = typeof(string))]
        [Route("updatemyexternalapp")]
        [ValidateHeader]
        [SwaggerHeader("x-api-key", "Client ID required - (eg:string)", "", true)]
        public IActionResult UpdateexternalApi([FromBody] UpdateexternalApiRequest model, [FromHeader(Name = "x-api-key")] string kid = null)
        {
            if (model is null) return BadRequest("Request form body empty - Please try again!");
            var response = _tstService.updateexternalApi(model);
            return Ok(response);
        }
}

namespace Services.Services
{
    public interface ItestService
    {
     string updateexternalApi(UpdateexternalApiRequest model);
    }

    public class TestService : ItestService
    {
    public string updateexternalApi(UpdateexternalApiRequest model){
     do some activity related in my database
     Task.Factory.StartNew(() =>ApiToExternalAPI());
     return 'saved successfully';
    }

public async Task<bool> ApiToExternalAPI()
{
    using (var client = new HttpClient())
    {
        ServicePointManager.SecurityProtocol |= SecurityProtocolType.Tls11 | SecurityProtocolType.Tls12;
        string ServiceUrl = 'url';
        string ServiceKey = 'key';
        client.BaseAddress = new Uri(ServiceUrl);
        client.DefaultRequestHeaders.Accept.Clear();
        client.DefaultRequestHeaders.Add("x-api-key", ServiceKey);
        client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", AccessToken); 
        client.DefaultRequestHeaders.Accept.Add(new         var response = await client.PostAsync(apiPath, formData).ConfigureAwait(false);
        var responseContent = await response.Content.ReadAsStringAsync();
        var value = false;
        if (response.IsSuccessStatusCode)
        {
            value = true;
        }
        else
        {
         value=false;
        }
        return value;
    }
}
    }