On PC with a Steam controller if that's relevant.
Questions's in the title, really. I can't figure out how to zoom in/out on a terminal. You can change the zoom on the Pip Boy using Back but that didn't do anything when using a terminal. Indeed, I've tried just about everything I can think of and nothing seems to work, zoom level on a terminal seems to be randomly changed.
It only ever seems to change when entering a terminal, I find I've never seen it change when using one.
Nobody else on the internet knows how it works either, I found a handful of Reddit/Steam threads with no definitive answers.