If you are using macOS 10.14.6+, you can accelerate applications with the external GPU (if they support GPU acceleration)...
Select the app in Finder
Get Info
Check Prefer External GPU
Adobe Premiere and Apple Final Cut Pro automatically use the eGPU when appropriate. Do not select Prefer External GPU for these applications.
Some professional applications let you select the external GPU (or multiple GPUs) in their preferences.
Connect one 4k monitor to the DP port.
Connect one 4k monitor to HDMI port.
Connect two 4k monitors a Sonnet Thunderbolt 3 to Dual DP or Dual HDMI adapter connected to the Thunderbolt 3 port.