Question about Resolution Scale Threshold

I understand leaving Resolution Scale at %100 720p, and tinkering with Threshold. What has never been made clear to me is if a game has to be restarted to apply effects, or do they apply in real time while the game is running. Think I would prefer the latter. Apologize if this question's been asked a thousand times.

Resolution Scale and Threshold are not dynamic values, so you need to restart.

Resolution Scale and Threshold are not dynamic values, so you need to restart.

That's a bummer. Thanks!