I just want to say as someone who doesn’t do 3D modeling himself and checks in to read this thread every once in awhile, it is both an informative, interesting thread and really cool to see the progress of your projects!
What UE provides is the environment and the mechanics for a variety of games and visual projects, including the backgrounds of shows like the Mandalorian.
Maybe shocking but I have done minimal technical modeling at this point, although I am "modeling" or maybe better said, composing /constructing a scene using the tools the Engine provides.
is the expert modeler here and if I understand it correctly, most actual modeling of things like buildings, objects, or characters are modeled in separate 3D programs like Blender then imported into Unreal Engine Editor.
For the last year I have been doing Unreal Engine tutorials, which the majority of it is providing an environment to put projects together. Now that "environment" in itself is a huge undertaking to understand it. I could learn to model trees, but at this point, there is no reason. A site called Megascans has huge numbers of modeled natural items free to access if you are using Unreal Engine. And those items, say for example a single boulder, can be manipulated in the engine to make it look different, and used multiple times across a scene.
Procedural Landscapes are huge because items there are repeated multiple, maybe hundreds of times, but for processing the engine counts them a 1 item. This ability makes authoring a game doable for a small team or even 1 person to accomplish. The biggest advantage I see is that not having to place every tree, the procedural settings adds a natural look to start with, and it can be edited to suit your specific needs.