Get Mat4 perspective of entity by the view of camera?

I’m trying to “bind” the DOM element to entity, the position is already obtained, but what about the projection?

How to get a plane matrix that would be usable for a DOM element, according to the camera view projection?

Are you looking to use CSS 3D to put the DOM over the plane? eg Perspective · Intro to CSS 3D transforms

Not sure how the perspective value is calculated in CSS myself. This now unsupported project did something like this so may help as a starting point.