Rendering objects to an off screen buffer like in Sea of Thieves

I was watching this video on how Sea of thieves did their clouds ( He goes over the whole process in about a minute. I was wondering how do you go about creating an off-screen buffer. Is that something I can do through blueprints and ue4’s materials or am I going to have to do what he described in that video through c++?

In blueprints, you would use SceneCapture2D and a texturerendertarget2d. But it is unaffordably slow for rendering anything, that is not an actual scene, and arguably can’t be used for anything but prototyping and ideally need to be done in code project/plugin/custom engine build.