Zoomed *in*? As in, font too large?
There is a way to adjust font size with the hardware volume buttons, perhaps you've accidentally made it too large, without knowing?
The adjustment is "sticky" from one message to the next, as it's considered to be a user preference.
Please try opening a message and press Volume Down a few times until it stops making the font smaller, then Volume Up twice. There are five steps total, and this should select the default size.
