Belts or bands of combined cotton with elastic has been used for quite some time to assist, encourage and guide primarily the child with “in-toe.” The in-toe is not from the foot but is from the hip-knee linkage or coupling.
These, like most orthoses are simply tools. Training tools that offer tactile cues, sensory input, proprioception and mild constraint of the swing phase limb as it is rotating inward. The elastics will not directly affect or change femoral antetorsion since this is an axial bone deformity of the femur.
The straps do not torque or twist the lower limbs outward. Instead, they discourage the unwanted internal rotations while still permitting desired internal rotation.
When sitting, playing on floor or through transitions of movement the elastics remain slack and without any effect on hip-knee-ankle.
Although we custom fabricate them in our office, they are available in both elastic and non-elastic materials from Cascade orthotics. https://cascadedafo.com/products/twister-straps