Resize Text requires that, aside from captions and images of text, text can be scaled up to 200 percent using standard browser zoom without breaking the layout, clipping content, or causing text to overlap other elements. Users need to be able to reach every feature and read every word at that zoom level.
This matters for people with low vision who do not use a dedicated screen magnifier but rely on browser zoom instead. Sites built with fixed pixel widths, fixed-height containers, or text set in images routinely fail this check, since the layout cannot flex to accommodate larger text.