Android 16 exposes a game mode through GameManager. A game can declare a preferred mode, read the current one, and register a callback for changes. The useful part for performance work is the callback: it fires when the system changes the mode because of thermals, battery saver or a user setting.
What the API does not give you is a performance promise. On three devices we tested, “performance” mode raised the sustained GPU clock on two and changed nothing on the third, which was already at its thermal limit. The callback still fired on all three, so the signal is reliable even when the effect is not.
Treat the callback as a hint to lower quality, not as a reason to raise it. The mode can be revoked mid-session, and a game that only handles the forward transition will spend the rest of the session at the wrong settings.