Render texture over entities texture in hiqh quality

So, what I want to do is render a texture over the existing player texture, but in high resolution. There’s the default player model, and on top of it, I want to render a mask when a button is pressed. This can be done fairly easily using Kleider's API, for example. However, I want the mask to be as detailed as possible—something like a 2048x1024 PNG.

How do I properly set up and render high-resolution textures like this in MCreator/Kleider's API? And how do I determine where exactly to draw the texture so that it aligns correctly with the player skin?