Options for making Ender 3 v2 fans quieter
There are companies making fans with blade design based on owl wings to make the blades quieter. Here's an example https://www.moduflow.co.uk/owlet-fans/ and I've seen other designs.  I don't know which design ended up being the quietest.  First, you would need to find out who makes these fans the right size and flow rate for you, then try to find out which is quietest.
Here is another example: https://www.bequiet.com/en/casefans/718