Completely uninstall an application
There are several 3rd-party “un-installers” available for Mac. The one I use is AppZapper.

There may be files in "~/Library/Application Support/{folder name of app}" and there may be a preference file in ~/Library/Preferences/.

Sandboxed apps have their data in "~/Library/Containers/{folder name of company}"

Some applications may also install more complicated things like kexts. Most of those apps will have their own uninstallers.