2019 5k iMac Graphics card upgrade

Good day,

I was wondering how I could upgrade my 2019 iMac 27 inch Graphics Card to something more substantial in order to handle flight simulators or even VR, I want something powerful enough to be able to handle requirements for the next few years. Really disappointed that this new iMac can hardly handle Final Cut editing or Lightroom editing....

Is there a method besides eGPU or is that my best bet??

Current System:

3.1 GHz 6-Core Intel Core i5

Radeon Pro 575X 4 GB

32Gb Ram

Thank you in advance for all your help!