If the leftie is forced to stop writing with left hand and switch to the right, is there any effect on the handwriting?

Yes, forcing a left-handed child to switch to writing with their right hand can have a significant negative effect on their handwriting. Their dominant hand (left) naturally possesses superior fine motor control, coordination, and dexterity for writing. When compelled to use their non-dominant right hand, they will likely experience reduced writing speed, poorer legibility, and increased fatigue, as that hand is not as developed for such intricate tasks.