Best phones for gaming without overheating

I want to get ahead of this before it becomes a habit. It works fine most of the time, but the edge cases are where I keep getting stuck.

Any pointers appreciated, even partial ones.

Slightly different take — do the cheap diagnostic first — it costs nothing and rules out half the causes.

Speaking as someone who got it wrong initially, the defaults are conservative on purpose, so there is usually headroom to gain.

Report back once you have tried it.