Power NodeMCU with 12v to 5v 3a - 15w DC-DC Converter?
Yes it should work fine. It seems overkill if you don't need waterproof and 3A of current.

If you are just looking for something cheap that works I did a quick search and found this: https://www.ebay.com.au/itm/DC-4-5-24V-to-DC-3V-15V-5V-9V-12V-1-2A-Buck-Converter-Step-down-Power-Regulator/332359897940?hash=item4d62319354:g:oZgAAOSwUT5ZlbW3

Either should work fine you can check their output voltage with a voltmeter before you connect it to the load.