Instantiate object as parent or child class without knowing which until constructor (PHP)

What's the best way to instantiate an object as either an instance of a parent class or an instance of a derived class, if you don't know which one to instantiate it as until after you start the instantiation (e.g., because the instantiation depends on data pulled from a database, which is only done during the instantiation within the class constructor)? Example:

class Thing { // parent class
  public $thing_type
  function __construct($thing_id) {
    /* database access code that sets $thing_type as either 'normal' or 'special' */
  }
  /* Accessor functions, etc. … */
}

class SpecialThing extends Thing { // child class
  function __construct($thing_id) {
    /* database access code that operates slightly differently that the parent constructor, */
    /* but which also sets $thing_type, presumably always as 'special'        */
  }
}

So I could do:

$thing = new Thing($thing_id);
if ($thing->thing_type == 'special') {
  unset($thing);
  $thing = new SpecialThing($thing_id);
}

but this seems wasteful because it involves running a whole constructor on an object that is promptly deleted, and involves two database calls instead of one. I was thinking maybe it might be possible to call the child constructor from the parent class somehow, like this (but probably not exactly like this):

class Thing { // parent class
  public $thing_type
  function __construct($thing_id) {
    /* database access code that sets $thing_type */
    if ($this->thing_type == 'special') {
      $this = new SpecialThing($thing_id);
    }
  }
  /* Accessor functions, etc. … */
}

But that still involves two database calls, even if it would work (not sure, haven't tried it).

There must be a "right" way to do what I want to do--I just don't know what it is.

The closest other stackoverflow question I found was this one, which suggests defining a constructor in the parent class that would take a parent object and copy all the properties into the new object. Then this constructor would be inherited to the child class, enabling creation of a child object by copying an existing parent object. But I'm not sure what this means or how to implement it.

(Using PHP 8.1.5.)