Change property of Modal windows with UXP

Hello everybody!
Could someone tell me if it is possible to change some properties of Modal windows " showModal({ title: “xxxx”, resize: “both”, size: { width: 400, height: 400} })" when loaded, such as yours size and especially the opacity “Opacity=0” as we already do with scriptUI - jsx. Please, is this possible, could someone show me how to do it? Thanks.

I don’t know if that’s exactly it, but from what I understand, I use the DOM.

testDialog.showModal(); = ‘250px’; = ‘550px’; = ‘url(/images/bgdial.png)’ = ‘7px’