It depends on the lens design, but the safest approach is: don’t force the focus ring while the lens is set to AF.

If the ring feels stiffer in AF, that suggests you’re working against the autofocus drive or its gearing, which can put extra stress on the mechanism. Being off the camera does not automatically make that safe.

A good rule of thumb is to switch the lens to manual focus first, then turn the ring. Some lenses are specifically designed for full-time manual focus override, such as certain Canon ring USM lenses or Nikon lenses with M/A-style manual override. On those, turning the ring in AF may be acceptable.

But if you feel resistance or hear unusual noise, stop. Unless the lens is explicitly designed for manual override, use MF before retracting or adjusting focus by hand.