I’ll start with the Porsche 997, the 996 looked alright imo, but it looks “like a 90s Porsche”, the 997 made it look sleeker and more modern. Still looks good today.
As for cars that looked worse after a facelift? Maybe the facelifted 6th gen Camaro? The 6th gen looked great pre-facelift, but they did something weird with the headlights and now it looks so-so…
I know it doesn’t quite answer your question, but if you have an hour to listen to a great podcast the carmudgeon show has an entire episode about facelifts (although they talk about more than just cosmetics, more like talking about mid cycle refreshes or “life cycle impulses”)