Google tells you more, If you want to completely delete junk files for Mac, maybe you are asked to install some software on your Mac to delete junk files .
I have installed this app on my Mac for cleaning up Mac : https://www.tunesbro.com/clean-junk-files-on-mac.html

Recently switched to Mac two months ago and I am wondering what kind of actions should I take to find and remove custom writing files on the device? The Mac runs slow after a recent update

Hi there,

MacKeeper blog has a good article - How to Clean Mac Storage. Or you may also look up the MacPaw How to section. A couple of tools I know and used myself: CleanMyMac, MacBooster, DaisyDisk.

Cheers,
Randy