Difference between query params and content-type: application/x-www-form-urlencoded

I have a simple yet very practical question. When we send a request using query params does Content-Type header application/x-www-form-urlencoded automatically set to that?

In other words when we send a POST request to any server just like

http://localhost:8080/api/setnewemail?email=newemail@google.com

Does it set the body of the request to the application/x-www-form-urlencoded or do I have to manually add this header and put the data email=newemail@google.com to the body and don't have to add the params to the url?

Thanks in advance