Be sure to check out the demo content on Unreal Marketplace, it’s got a lot of fantastic free demo projects.
For example doors opening and closing, there’s the “Blueprints” (titled as such) demo project on Unreal Marketplace.
Since you’re familiar with offline 3D (knowing Blender nodes and node-based workflow etc. helps), you should be able to get into UE4 fairly smoothly.
As you would with offline 3D, set up all your assets accordingly in UE4. Animations can be a little tricky but it’s quite logical in UE4 in my opinion. Then use Blueprints to make it all “come alive”.
There’s plenty of tools and tutorials for moving between UE4 and Blender so going back and forth with that should be straightforward.
For 2D I’m not familiar with that so will leave it to someone else.