If you are not familiar with modules, check out Ansible - Getting Started with Modules.

ansible.builtin.uri can be used to submit a POST request to an API. For example, here is how you could submit a POST request to http://example.com/api/v1.

---
- hosts: all
  tasks:
  - name: submit a POST request to http://example.com/api/v1
    ansible.builtin.uri:
      url: http://example.com/api/v1
      method: POST
...

Sometimes the API will return a response code that Ansible thinks indicates that the POST request failed, when in fact the POST request was successful. For example, I had an REST API that was returning a status code of 204 when the reqeust was successful, and Ansible interpreted this as a failure. To account for this, I added failed_when so that the task was not failed when the response code was 204.

---
- hosts: all
  tasks:
  - name: submit a POST request to http://example.com/api/v1
    ansible.builtin.uri:
      url: http://example.com/api/v1
      method: POST
    register: out
    failed_when: out.status != 204      
...

If the API requires basic authentication, these options can be included.

• force_basic_auth
• url_username
• url_password

---
- hosts: all
  tasks:
  - name: submit POST request to http://example.com/api/v1
    ansible.builtin.uri:
      url: http://example.com/api/v1
      method: POST
      force_basic_auth: yes
      url_username: john.doe
      url_password: itsasecret
...

If you want to POST payload data to the API, body and body_format can be used. For example, to POST JSON.

---
- hosts: all
  tasks:
  - name: submit POST request to http://example.com/api/v1
    ansible.builtin.uri:
      url: http://example.com/api/v1
      method: POST
      body_format: json
      body: "{ \"foo\": \"bar\" }"
...

If the URL includes parameters (key/value pairs), you may want or need to include body_format: form-urlencoded.

---
- hosts: all
  tasks:
  - name: submit POST request to http://example.com/api/v1?foo=hello&bar=world
    ansible.builtin.uri:
      url: http://example.com/api/v1?foo=hello&bar=world
      method: POST
      body_format: form-urlencoded
...

And here is an example with an oAuth bearer token passed in as a header.

---
- hosts: all
  tasks:
  - name: submit POST request to http://example.com/api/v1
    ansible.builtin.uri:
      url: http://example.com/api/v1
      method: POST
      headers:
        Authorization: "Bearer abc123"
        Accept: application/json
        Content-Type: application/json
...

If the POST request is successful, something like this should be returned.

ok: [server1.example.com] => {
    "out": {
        "msg": "[200]: OK", 
        "pragma": "no-cache", 
        "redirected": false, 
        "server": "******", 
        "set_cookie": "JSESSIONID=7B01203DD8CA499717F5BD3B36A6D929; Path=/example; HttpOnly; SameSite=Strict", 
        "status": 200, 
        "url": "http://example.com/api/v1?foo=hello&bar=world", 
        "x_content_type_options": "NOSNIFF", 
        "x_frame_options": "SAMEORIGIN", 
        "x_xss_protection": "1; mode=block"
     }

If you will be passing in unique URL string, it's probably a good idea to use set_fact and urlencode.

---
- hosts: all
  tasks:
  - ansible.builtin.set_fact:
      my_url: input_string | urlencode

  - name: submit POST request
    ansible.builtin.uri:
      url: "{{ my_url }}"
      method: POST
      body_format: form-urlencoded
...