how to add a new entity display like the player when you open the inventory

[DarkiDoki]

I am trying to make a mod where you can add a Steve model or Alex model and then switch between them like a morph. How do I add a model display for the selected model? The only thing I have been able to find is the PlayerEntity in the PlayerInventory... but I can't find where in the code (1.19.2) that actually makes the Entity be displayed in the position it's at in the inventory or the code that creates the displayed model in general.
I need to import a JSON model file of an Alex and Steve model and then I need the code that adds them to my GUI display. Any ideas on what I can do?

[warjort]

The code you are looking for is in InventoryScreen.drawEntity()
Not sure how useful that is for what you are doing?
It requires a player and will use their skin along with drawing other stuff like the worn armor.

You probably want to look at PlayerEntityRenderer and its parent class(es).
The models are created programmatically and the vanilla game has 2 instances of this class
default and slim which are steve and alex
see the EntityRenderers.PLAYER_RENDERER_FACTORIES