It appears that lens is discontinued, but I found a couple selling used at B&H Photo, and they have the specifications for the lens available.
The highest magnification possible with the lens is 1:4 or 0.25X... on quarter "life size", which is a little better than a lot of zooms, but not really "macro" by most peoples' definitions.
There is no "official" definition of what constitutes "Macro". Some think only 1:1, 1.0X or "life size" qualifies. Others refer to 1:2, 0.50X or "half life" size, which was the highest magnification possible with many older macro lenses, without added accessories. Few zoom lenses come anywhere close to even 1:2, let alone 1:1 magnification. But many zoom lenses "claim" macro capabilities for marketing purposes. In truth, they're more like "close-up" capable zooms. (An exception is Canon's EF 24-70mm f/4L IS USM zoom, which can do 0.70X or almost "three quarters life size" on it's own, using its "macro" setting.)
The specifications for the lens lists 15 inches (.38 meter) as the closest focus distance (or "MFD", "minimum focus distance") of the lens. This dimension is measured from the film/sensor plane of the camera. But this only renders 1:4 or 0.25X magnification, maximum.
If you want greater than 1:4/0.25X magnification with the lens, you can fit "macro extension tube(s)" between the lens and the camera. WHOOPS! I see that Kenko, Vello, Fotodiox, and others offer those tubes in sets (apparently most sets include two.... 10mm and 16mm... which can be used together for 26mm). These tube sets provide electronic connectivity for focusing, aperture control and any other lens functionality. SEE EDIT BELOW.
DO NOT buy the cheaper macro extension tubes that don't have the electronic contacts. Those will provide higher magnification, but no means of auto focusing the lens and... far more importantly... no control over the lens aperture. Those cheap tubes (many cost under $10) might be useful with vintage, manually focused lenses that have built-in mechanical means of controlling the lens aperture. But they are largely unusable with modern, electronically controlled lenses.
IMPORTANT EDIT: Forget the Kenko, Vello, Fotodioz lenses mentioned above. Those are all Sony E-mount and will not work with A-mount cameras and lenses such as your 18-70mm. For use with your lens you need A-mount extension tubes. There may be others I'm unaware of, but I found the following two possibilities:
Kenko A-mount Extension Tube set (12mm, 20mm, 36mm):
https://www.adorama.com/knaetsdmax.html?utm_medium=cpc&utm_source=adl-gbaseMovo A-mount Extension Tube set (10mm, 16mm, 21mm):
https://express.google.com/u/0/product/678369844010318091_8620204774974029592_100176220?utm_source=google_shopping&utm_medium=tu_cu&utm_content=eid-lsjeuxoeqt>im=CPS_ue3pgqOSBBDd6vbL346lowkYsLvULyIDVVNEKJD4quwFMNyi4i8&utm_campaign=100176220&gclid=Cj0KCQjwiILsBRCGARIsAHKQWLN1RtxZgZ_juVkcRBrIyf5aNk_ZQRA6Fb8_6a68Zh9oaqT8vBy0oYMaAgvPEALw_wcBExtension tubes such as these are an easy way to make any lens that fits your camera able to focus closer. You can increase magnification by adding more extension. While the extension is installed, the lens will not be able to focus all the way to infinity.
I learned to use extension tubes many years ago and have made a point of having a set of them handy for every system I've used since, they're so widely useful while being reasonably affordable (compare to buying a macro lens), light weight and compact.