Start with the downloaded dimensions
A JPEG contains a fixed number of pixels. Changing a DPI label does not create more image detail. The studio reads the downloaded JPEG dimensions before producing a layout and reports those dimensions alongside the proposed print size.
For example, 1686 pixels spread across 5.62 inches correspond to 300 pixels per inch. The same pixels spread across 11.24 inches correspond to 150 PPI. These figures describe sampling density, not an absolute promise of sharpness on every printer or at every viewing distance.
Account for the actual image opening
Paper size includes the white border. Fit mode preserves the image ratio and can leave additional white space, so the printed image may be smaller than the opening in one dimension. Center crop fills the opening by clipping the excess image.
The effective PPI calculation uses the scale at which the source pixels are drawn. The crop report shows the proportion of image area removed. A crop can improve composition for a particular frame, but it cannot recover detail that is absent from the download.
Test the physical output
The PDF page has the requested physical dimensions. Print at actual size and turn off fit-to-page scaling. Check whether your printer can handle that paper size and whether its unprintable margins conflict with the chosen border.
A sample print is the best way to assess paper, ink, viewing distance and color. The studio embeds the downloaded JPEG rather than pretending to generate a color proof or a higher-resolution master. Reduce the print size if the reported PPI is too low for your needs.