Phantom Forces IK

Hello, so I’ve came around seeing many R6 footplanting modules such as this one:
R6 IK module

I was wondering how I go about recreating something similar to this video’s
DevDump R6 Footplanting

I could not wrap my head around this with the limited knowledge I have, Could someone show me an example or show me how to recreate the foot planting seen in the video that is also animation compatible.
Thanks!