The Network_Features map inside the Content Examples project illustrates how to implement network functionality entirely through Blueprints. It provides key examples in Replication including the Replicates boolean which can be set on Actors, detecting Network Authority and executing different logic based on that authority, usage of Variable Replication and how it is used during gameplay, variable replication using RepNotify to execute logic based on updates made to a variable that is replicated, as well as the use of Function Replication to handle non-critical gameplay elements or "one-off" events.
The other section in the map provides insight on Relevancy and how to properly handle communicating information to and from the Server and Clients. Often times, it is not critical that every bit of information be passed from the server to every client (e.g. a player that is on one side of the map does not need to know about another player opening a chest on the other side of the map). There are situations when this would become relevant to that player however (e.g. if that player moved from the other side of the map to the chest that was opened), the Content Examples in this map will show how to handle situations like this as well as how to handle a player that joins an in progress session.
You can find additional resources on how an example was constructed by clicking on the example's name in their respective tables.