Is the secret flag "chrome://flags/#max-tiles-for-interest-area" a legit trick or scam? I've been seeing these "secret flags" (e.g. chrome://flags/#max-tiles-for-interest-area) for Chrome browser on Android posted all over the internet.

Are these legitimate tricks, or scams to phish users?
Chrome flags (accessed by going to chrome://flags on Chrome) are basically on/off switches for experimental and dangerous (hence the warning at the top of the flags page) features not yet officially announced in a Chrome release.

They are most definitely not scams, but are experiments intended for testing by developers and beta testers of Chrome.