I tried to do this a few times but It failed
I tried find solutions on roblox forum but I didn’t find It. Also I found a lot of free R6 footplanting systems but I want to make my own system because I want learn something new
Raycast originating from your character to the bottom direction Vector3.new(0, -1, 0)
Find the motor6d connecting the torso to any leg and change the C0 cframe to match how high or low the raycast hit in the floor
IKControl would make the work easier but wont function properly on r6 characters mainly because the chainroot (property in ikcontrol to determine where the joints transformation will originate from) must belong the same limb or body part like foot to upper leg
so just dont use ikcontrol
I know 2 modules that makes IK for R6 like CCDIK or R6 Inverse Kinematics Module