Because ALL the animations will be constant you can raise the feet by the heel amount.
You do this by just shifting the whole mesh (master pose) up however many centimeters.
You then have to apply a rotation - i would suggest a corrective animation, as it would be best - to angle the feet according to the shoe. Or, you could replace the feet mesh.
if you just weight paint the mesh to use the flat position it would be fine.
you just need to shift the feet down without altering the bones.
Keep in mind, walking in heels should probably be its own animation…