How to swap the texture of a 2D polygon in Godot 3.6 at runtime?

So let's say my character has a Skeleton2D and polygons to make the rig. I need to swap the texture of the clothes that it uses.
How to change it?

var my_p: Polygon2D = Polygon2D.new()

func _process():
    my_p.texture = new_texture

kuligs2 func _process():
my_p.texture = new_texture

Of course, that's only an example. You don't want to reload the texture every time _process() is executed.