Reduce If Else condition in ASP.Net MVC

Hi,

Could someone please help me to refactor the "if else code" below in a more simplified way:

public async Task<IActionResult> GetEtasjeAsync(
[HttpTrigger(AuthorizationLevel.Anonymous, "get", Route = "etasjer")]
HttpRequest req, ILogger log)
{
    try
    {
        // Check if there is an access token to authorize the call to this endpoint
        var accessToken = _azureAdJwtBearerValidation.GetAccessToken(req);
 
        if (accessToken == null) return new UnauthorizedResult();
 
        // validate that the access token is valid by checking that the signature is valid
        var validateAccessToken = await _azureAdJwtBearerValidation.ValidateAccessTokenAsync(accessToken, log);
 
        if (validateAccessToken == null) return new UnauthorizedResult();
 
        var param = "page";
        var param1 = "size";
 
        if (req.Query.ContainsKey(param) && !req.Query.ContainsKey(param1))
        {
            if (int.TryParse(req.Query[param], out var number) && !int.TryParse(req.Query[param1], out var size))
            {
                if (number > 0 )
                {
                    var result = await _services.EtasjeQueryServiceAsync(req, number, 1000);
 
                    if (result == null) return new NotFoundResult();
 
                    if (result.Content.Count == 0) return new NoContentResult();
 
                    return new OkObjectResult(result);
                }
                return new BadRequestResult();
            }
            return new BadRequestResult();
        }
        else if(req.Query.ContainsKey(param1) && !req.Query.ContainsKey(param))
        {
            if(int.TryParse(req.Query[param1], out var size) && !int.TryParse(req.Query[param], out var number))
            {
                if(size > 0)
                {
                    var result = await _services.EtasjeQueryServiceAsync(req, 1, size);
 
                    if (result == null) return new NotFoundResult();
 
                    if (result.Content.Count == 0) return new NoContentResult();
 
                    return new OkObjectResult(result);
                }
                return new BadRequestResult();
            }
            return new BadRequestResult();
        }
        else if(req.Query.ContainsKey(param) && req.Query.ContainsKey(param1))
        {
            if(int.TryParse(req.Query[param], out var number) && int.TryParse(req.Query[param1], out var size))
            {
                if(number > 0 && size > 0)
                {
                    var result = await _services.EtasjeQueryServiceAsync(req, number, size);
 
                    if (result == null) return new NotFoundResult();
 
                    if (result.Content.Count == 0) return new NoContentResult();
 
                    return new OkObjectResult(result);
                }
                return new BadRequestResult();
            }
            return new BadRequestResult();
        }
        else if (!req.Query.ContainsKey(param) && !req.Query.ContainsKey(param1))
        {
            if (!int.TryParse(req.Query[param], out var number) && !int.TryParse(req.Query[param1], out var size))
            {                      
                var result = await _services.EtasjeQueryServiceAsync(req, 1, 1000);
 
                if (result == null) return new NotFoundResult();
 
                if (result.Content.Count == 0) return new NoContentResult();
 
                return new OkObjectResult(result);
            }
            return new BadRequestResult();
        }
         
        var response = await _services.EtasjeServiceAsync(1, 1000, req);
 
        if (response == null) return new NotFoundResult();
 
        if (response.Content.Count == 0) return new NoContentResult();
 
        return new OkObjectResult(response);
    }
    catch (Exception ex)
    {
        log.LogError(ex, ex.Message);
        throw;
    }
}