I am looking a way to draw a trapezoid limit inside Fit Y by X chart or graph builder like excel example below. Any idea?

If you right click on the graph, you can Customize the graph, which will allow you to add the graphics you want to the chart.

Here is what the customization window looks like

And here is the simple graphic code required
pen color("blue");
pen size(2);
line([.273, .292, .339,.319,.273 ], [.279, .334, .359,.302,.279]);
Marker Size( 5 );
Marker(
color state( blue ),
Marker State( 15 ),
[.273, .292, .339,.319],
[.279, .334, .359,.302]
);
Sorry, I do not know off hand, so I'll let others chime in. What is the criteria you want to use to create the trapezoid? Why do you want this?