anyway, here is my quick + dirty findings. make of them what you will (click to enlarge images). the thing i noticed is that my CPU never goes above 4.8GHz so that would indicate whatever process is causing the rise in usage/temps is an AVX instruction. i have a -2 AVX offset. CPU is meant to run at 5.0GHz unless there is an AVX load in which case it will downclock to 4.8GHz. look at CPU temperature/usage and it seems that the Epic Client is also using my GPU which shows increased usage/temps.
To be fair some (specially the smaller games) are actually DRM free.
You can, for example, install Into the Breach, then uninstall the Epic launcher and it will still work (you just need to move it from the default install location because otherwise it will get automatically removed when you uninstall the launcher)