The product brochure of the new Tamron 70-300mm f/4.5-6.3 Di III RXD lens for Sony E-mount (model A047) leaked online (see previous leaks). The retail price of the lens in Japan will be 63,800 yen including tax. The planned release date is October 29, 2020.
Here are all Tamron full-frame mirrorless lenses for Sony E-mount:
Via Nokishita