I doubt anyone will answer this question with the information you seek. The topic is too big and the question is too general.
Also, in the strictest sense, there is no such thing as a real-time MMO. Low-latency MMO, or MMO with predictive movement to hide latency, yes, but not real-time.
You’ll only get (near) real-time anything if all inputs and responses to inputs are handled on the same device.
Lastly, if this was a serious question, and if you are new to game development, I’d strongly suggest you not start by trying to make an MMO. To make one requires significant experience, skill, and a team. Maybe start with a single-player RPG instead?
One last note, if you’re asking merely as an exercise or out of curiosity, then please ping me back and I’ll give you a brain dump of some of thing (many) things you’d have to do to make (any) multi-player game.