There is this janky early-access game that I try recently and another good one, Everspace 2.

In Everspace 2, I really like how you can force lower frame rate when the game is not in foreground (when alt-tab to another window)

In GameUserSettings.ini under [/Script/ES2.ESGameUserSettings] there is

FpsLimitNoFocus=30
...
bFPSCapEnabled=True
CappedFPS=60

Are these implemented by dev themselves or are they available at engine level on all UE4 games? Is there a way to do this on other games that do not have this in-game config?