Mac storage basics · Library folders explained
Can I delete .plist preference files to save space?
Short answer: You can, but they're tiny settings files, so you'll save almost nothing — and you'll reset that app's settings. Look at caches, media and app data for real space.
You can, but it won't save meaningful space. Preference files (ending in .plist, in the Preferences folder of your Library) are tiny settings files — even hundreds of them rarely add up to much.
Deleting one resets that app's settings, which is occasionally useful for fixing a misbehaving app (quit it first). For freeing space, look at caches, downloads, media and app data instead — see what uses the most space.