From what I can see there are helper methods inside the ControllerBase class. Just use the StatusCode method:
[HttpPost]
public IActionResult Post([FromBody] string something)
{
//...
try
{
DoSomething();
}
catch(Exception e)
{
LogException(e);
return StatusCode(500);
}
}
You may also use the StatusCode(int statusCode, object value) overload which also negotiates the content.