How to use 'get_titlebar_hbox()'

Help
,
1

I’m learning about how to make plugin!
And now I need some advice about graph node

What I’m curious about is how to change the font of the title of the graphic node

I looked it up on Google and they told me to use ‘get_titlebar_hbox()’, but how do I use it to change the font of the title?

The code below was not very useful

@tool
extends Control

@onready var graph_node = $graphnode

func _ready() -> void:
    graph_node.get_titlebar_hbox(lable)

Could anyone help me with this?

If this method is not valid, could you please tell me how to remove the title altogether and fill it with panels only?