ue5-multiworld-demo VS GASContent

Maybe you could get a better idea of what it does with the pre-built demo: https://github.com/UNAmedia/ue5-multiworld-demo/releases

Secondary Worlds are not network replicated, but you can send RPCs from them. We have an example of it in our sample project on GitHub (https://github.com/UNAmedia/ue5-multiworld-demo), where the changes in the client inventory (a Secondary World) are sent to the server to network-replicate them to all the clients.

The technique you mention is used in the demo application (https://github.com/UNAmedia/ue4-multiworld-demo - there’s also a build ready to download) to showcase a possible use in a multiplayer game: the main world is network-replicated, while a secondary world is used as an “inventory” scene to change the player attributes. While the secondary world is technically not network replicated, it simply calls methods on the actors in the main worlds to take advantage of network replication, replicating the player changes to all the connected clients (using the standard replication system of UE4). I thin in the demo there’s a better description :)

Here is the most useful collection of documentation and project examples I've ever found in the internet: https://github.com/Pantong51/GASContent

It is on the fair bit complex side of things, tho. Which if you are a beginner/blueprint-only, isn't going to fun. You would need a basic level of c++ and a good understanding of blueprints, plus the documentation for that system is shoddy. Here is a collection of resources for learning about GAS, if you wanna give it a go.