You would have to create an actual script or elaborately rig up your project with expressions so they e.g. change stuff based on external JSON files. All explained in the online help. However, based on such generic and vague descriptions nobody can advise specifically. And to be honest, around 20 videos only is peanuts. You could do it faster by hand and setting up the automation would take a lot longer. It's merely a matter of methodically duplicating the comp(s) and replacing the relevant parts, then adding it to the render queue. Sounds like you're overcomplicating this and looking for shortcuts when all it takes is an hour of meticulous, patient work.