Is there an adapter / Dock / hub with 2 display outputs?
A lots of Thunderbolt 3 docks exists that will allow you to have 2 display outputs. Usually these are organized such that one display is connected to an HDMI or DisplayPort output on the dock, and the other is connected to the chained Thunderbolt 3 port on the dock which is used as a DisplayPort output.

For example you could use the Elgato Thunderbolt 3 Dock, the OWC Thunderbolt 3 Dock or the Caldigit Thuderbolt Station 3.

Note: Before you rush out and buy any of these make sure that you actually have got a Thunderbolt 3 enabled MacBook Pro or similar. Your question contains conflicting information as you claim to have a MacBook with Thunderbolt 3, which doesn't exist. The MacBook (2015, 2016 and 2017) have USB-C only.