yes, the RL "Water Wetter". has been around a LONG time. I remember at some point adding it to some Ethylene Glycol radiator fill. but any result with it would be purely anecdotal. high heat can be "kinda" an issue out here in the desert. I don't know, IMO if you got a temp gauge on high you have other things that need addressing well beyond just adding a quart of any of that stuff.
EDIT: FWIW running more distilled water and least amount of antifreeze possible during the very hottest months would IMO be a better solution. and then maybe add a bottle of that stuff to that. I'm sure it has a bunch of good corrosion inhibitors in it.
We did exactly that for generator sets deployed in Saudi Arabia, Iraq, and Afghanistan.
The engines were filled with distilled water and additives (anti-corrosion, water pump lube, anti-cavitation since these were all diesels).
They get about another 5-10 degrees F of cooling @ rating full load.
Glycol antifreeze has a much lower specific heat absorption than pure water.
But pure water boils at something like 230F under 15 psi whereas 50/50 coolant boils around 265F. At sea level.
So you got to know what you're doing with lower alarms, and cooling system size.