Finally, the exact announcement date for Canon EOS R5, EOS R6, and 6 new RF lenses & 2 teleconverters now confirmed, these new products will be officially announced on July 9th, 2020. CR has also leaked the new Canon RF mount lineup image above. The RF 600mm DO & RF 800mm DO IS STM lenses are in silver color.
Chinese website Xitek has a chance to take some photos of upcoming Canon EOS R5. Above is the Canon EOS R5 compared with Canon EOS R and Canon EOS RP. From the image, we can see that Canon EOS R5 has similar size as Canon EOS R, while bigger than Canon EOS RP.