Would this work to convert the 24v that comes from the mainboard to the fan into 12v for the new fan?

Maybe something like this: https://www.amazon.com/Onyehn-Adjustable-Regulator-Step-Down-Converter/dp/B07G59J3TL/ref=sr_1_13?crid=H0VXSPPQYAQ1&keywords=lm317&qid=1642906927&sprefix=LM317%2Caps%2C46&sr=8-13 ??

Although that one doesn't give a height dimension it looks like it might work.

My worry is that I don't know how just a 7812 works so I'm not sure if it would do what I want it to without a board supporting it and or a big old heatsink or something like that.