How are a cartoon character's feet fixed to the floor?

Hello, I watched a video. I am sharing this video as a link below. From the 43rd second of this video, when the character moves right, left, down and up, his feet remain fixed on a certain ground. So his feet seem stuck to the floor and his torso is playing. I want to implement this. How do their feet and other limbs move proportionally within themselves? So how can I keep my feet steady on the floor.

VIDEO LINK (YOUTUBE): Toon Boom Harmony Character rig Demo - Master controllers & deformers - YouTube

I did one for aircraft undercarriages on my website, well two actually, the same principles apply to character rigs. Just place a bone at the end of the chain, add an IK Constraint to the bone before that one (the current last one in your leg chain) and set the chain length to the number of bones in either the leg or arm, both two in your case. IK chains MUST target the tail of a bone, this also enables you to move and place this target bone. The length and orientation of this bone are not important, but I suggest you make it obvious and reasonable to see and move.
As I said, the principles are the same, just the application slightly different - you should be able to relate the IK sections of these aircraft tutorials to the skeleton file I posted above.

Don’t forget the “Master Bone” on the floor! This makes moving the whole character much easier.

Good Luck,

Video Animation Studio