I’ve seen some fake fireplaces that use steam and lights to look like fire, you could use steam from waste heat from the fusion reactor?

Plasma for fusion is at insane temperature and pressure to make fusion possible, to overcome the repulsive force that keeps protons apart by sheer velocity of the colliding nuclei. So you wouldn’t have that kind of plasma in a fireplace generally. But you can get room temperature plasma today without fusion, look up plasma balls… That could make a cool (but not fire-like) fireplace, if it could be engineered into another form factor