Update: Vivo has just spoiled the S5's reveal as far as esthetics go. The new image posted to this OEM's official Weibo channel shows a central, squircle-like rear-panel feature. It also confirms 2 of the phone's main camera specs: it has a quad-lens set-up (only 3 of which fit into the diamond module), the primary shooter of which is 48MP in resolution.
The Vivo S5, like the S1 Pro, is shaping up to be an interesting mid-range phone with some more premium features. It already has an official page on the OEM's Chinese online shop; however, every detail thereon is a placeholder. However, a leak associated with the phone suggest decent specs with features often associated with higher-end devices.
According to this tip, posted to the social media site Weibo, the Vivo S5 will be powered by the Snapdragon 712 SoC. It may have a 6.44-inch FHD+ AMOLED display and quad 48+8+5+2MP rear cameras. This phone is also touted to have an 8GB RAM variant and a 4100mAh battery that charges using this OEM's 22.5-watt standard.
The Vivo S5 is also known to have a punch-hole selfie camera, which is said to house a single 32MP module. It will be revealed on November 14, 2019, apparently in conjunction with the Chinese celebrity Cai Xukun. This may explain the "Ikun Custom Gift Box" in which the S5 is displayed on its sales page.