Seeing your question got me thinking if I have used any graph based UI other than the one in Blender.
Blender has a thing called geometry nodes which are used
for procedurally and non-destructively creating and manipulating geometry.
Going through Wikipedia I learned that this is called Procedural modelling.
Other similar UIs I realized I've used are in Jeskola Buzz, a digital music workstation and Max / Msp inside Ableton Live.
From there I got bit deeper when I tried to find the first instance of this kind of no-code UI. You can for example read upon about visual programming language. Or go one level deeper with dataflow programming.
But when it comes to actual presentation as in Unreal or in Blender, I didn't yet find any standardized design patterns for it. It might just be a case of copying what has worked.
I did find Blender's take on the node based UI in their developer documentation, though. It has some high level concepts on the node behaviour.
The "Geometry Nodes Modifier", or "Nodes Modifier" for short, is a a modifier to handle more complex behavior. Its logic is built with a node group owned by the modifier. The geometry node group which can be used by multiple modifiers on different objects, or shared for different projects, just like a shader node group. High level settings are exposed in the modifier stack.
It also has the high level abstraction of the modifiers (nodes), which the one we can see also on the Unreal's UI.
Modifiers are black boxes with geometry as the main input and output. External dependencies are possible on ID level. Users should be able to use the system in a high level. More general nodes contain several lower level building block nodes, with certain parameters exposed.
