The Razer Blade Stealth has a lot of great features such as support of HDMI 2.0 and the Razer Core external graphics docking station, but unfortunately it doesn't support dual 4K@60hz displays. This means that products like the Plugable Thunderbolt 3 Dual DisplayPort Adapter can't connect two 4K display to the Razer Blade Stealth.
We first plugged the Plugable Thunderbolt 3 Dual DisplayPort Adapter into the Thunderbolt 3 port of the Razer Blade Stealth, and approved the Thunderbolt device.
However, the Intel HD Graphics Control Panel could only show one of the 4K displays that was connected to the Plugable Thunderbolt 3 Dual DisplayPort Adapter at a time.