Perhaps but on my phone I can zoom in and out real fast on a page of text without a single glitch or hiccup and there’s no way a >512px bitmap for every character displayed is used.
If you were to do a slow motion video of what’s happening, what you would see is that it’s the bitmap that’s zoomed and then the zoomed bitmap gets replaced with a rendering of the outlines. It is not re-rendering outlines at every zoom level.