Module development and code questions

When searching online I have seen multiple answers to this question and I wondered if anyone could tell me the correct way? php.ini? cpanel? Drupal configuration? Apologies for such as basic question but I'm learning. Thanks!

I have created a Rest API to create a user after success full user creation created CSRF token for the further user access. created csrf token using below core functions. using get() - function i am able to get a csrf token.
public function get($value = '') {

    $seed = $this->sessionMetadata->getCsrfTokenSeed();

    if (empty($seed)) {

      $seed = Crypt::randomBytesBase64();

      $this->sessionMetadata->setCsrfTokenSeed($seed);

    }

    return $this->computeToken($seed, $value);

  }

Is there a way where we can skip the drupal 10 default xcsrf token validation and alternatively can add the token programatically.

I have been trying to integrate the xcsrf token and when i integrated with my Rest API it is not working as expected

1. method

Core service = \Drupal::service('csrf_token')->get();

2. method

          $url = Url::fromUri('base:/session/token', ['absolute' => TRUE])->toString();

          $response = \Drupal::httpClient()->get($url);

          $user_csrf = $response->getBody()->getContents();

          $csrf_token = trim($user_csrf);

I wanna upload a image in an Api service when i upload them using postman got a below error - need to enable/add multipart/form-data in server accept area
"415 - Unsupported Media Type" - uploaded under form-data

Drupal 7 

Drupal 10 limits the accept parameters as below