If I assign an Object as GameObject, I cant get the RectTransform to work. How to fix that?

I want to give my Parent GameObject Inventory spicific rec-coordinates via this line of code:
Inventory.GetComponent<RectTransform>().position = new Vector3(500f, 0f, 0f);

In the editor, the object Inventory is assigned as a GameObject, so it keeps changing the rec-coordinates to world-coordinates. I’ve tried assigning the Inventory as a Transform and RectTransform but it says that there is a missmatch in the type.

How can I fix that, either by fixing my code or by assigning it as something different?

>Solution :

You should modify the RectTransform’s localPosition:

Inventory.GetComponent<RectTransform>().localPosition = new Vector3(500f, 0f, 0f);