They are available in a very wide range of magnifications. Magnifying lenses may also have built-in lighting.
Regardless of whether they are handheld or based on a stand (tabletop), magnifiers are intended for occasional use, e.g. for a phone number or an expiration date. They are not suitable for reading because they tire the visual system, as the magnification is such that the letters cannot fit into our field of vision.
Magnifying glasses are more useful to people who do not have low vision and want to see just greater detail, such as stamps.