Jumping is replicated, it’s part of a bit flag system that the character movement component uses, the component has some flags like bWantsToCrouch and bWantsToJump, these flags are set by the client when you press a button to jump for example, gets simulate client side and those flags are sent to the server and the server does the same simulation and network prediction/replication.
I recommend watching a video about extending the character movement component for adding other modes and flags it’s the same concept applied to crouch and jump.