Things that might be helpful to know (Agenda version, OS and model, etc): agenda 5.1 (69), High Sierra 10.13.6, macbook pro 2017
There’s currently no way to change between left, center, and right aligned text. At this point we don’t have plans to add this I’m afraid, that’s more the realm of a text editor than a note taking app. Do note that you can use indentation to “center” text.