When zooming text with the pinching gesture with two fingers, it should automatically adjust text position to match the screen edges and automatically reflow text to fit them. This is specially important on iPhone, as the screen space is very limited. It could be an option in the settings, to allow both ways.
The desired behaviour can be found, for instance, in an app named Permanote (formerly Nebulous Notes). You pinch the screen and the text adjusts its size and fits the screen, fowing in realtime.
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