Plan for multiplayer early
If there is a possibility, that your project might need multiplayer features at any time, you should build all of your gameplay with multiplayer in mind from the start of the project. If your team consistently implements the extra steps for creating multiplayer, the process of building gameplay will not be much more time-consuming compared with a single-player game. In the long run, your project will be easier for your team as a whole to debug and service. Meanwhile, any gameplay programmed for multiplayer in Unreal Engine will still work in single-player.
https://docs.unrealengine.com/5.0/en-US/networking-overview-for-unreal-engine/