Difference between proxy in class constructor vs proxy with construct handler

Question

I'm finding different implementations to hook all instances of a class to a proxy.

Inside the class constructor (example):

class Foo {
  constructor(...args) {
    //...

    return new Proxy(this, {
      //...
    });
  }
}

With the construct handler (example):

class Foo {
  constructor(...args) {
    //...
  }
}

new Proxy(Foo, {
  construct(Foo, args, newTarget) {
    // ...
    return Reflect.construct(Foo, [...args], newTarget);
  },
  //...
});

Is there a difference in these implementations? I want to make a generic setter and getter; so in the second alternative I would have to create a proxy inside the proxy, which in terms of memory allocation and performance would be the same I think.

Is it so?