1. You should almost always use requests.Session() instead of requests. It's faster, and can make the code shorter.

2. requests can dump to JSON for you by using json=, so you don't need a separate module. It'll even set the content-type header to application/json for you.

  import requests
  
  url = '<endpoint>'
  
  headers = {
      'User-Agent': 'Mozilla/5.0 ...',
      ...
  }
  
  session = requests.Session()
  session.headers.update(headers)
 
  data = {
      "page": 5,
      "size": 28
      ...
  }
  
  response = session.post(url, json=data)
  
  if response.status_code == 200:
      print(response.json())
  else:
      print(f"Error {response.status_code}: {response.text}")