I maintain a small repository of free sound effects I have made with my Borg ER-3 tone generator project: https://github.com/mrbid/Sound-Effects

These are free to use, although I tend not to use sound in my games these days because I find it a bit tacky and annoying in video games, I can finally appreciate why adults used to get so frustrated by the crunchy noises coming from my GameBoy as a child.

Other sound effect archives you may be interested in:

1001 Sound Effects (*free)
App FX (paid)
BBC Complete Sound Effects Library (paid)
BBC Rewind Sound Effects (*free)
Sound Ideas Sond Effects Library 1000 (paid)

Sound Ideas released a lot of sound effect packs, such as the Warner Bros Sound Effects Library.

And ofc... https://freesound.org/

My first ever sound effect libraries where:
https://www.amazon.co.uk/Sound-Effects-Vol-Machines-Movement/dp/B000M4RCX2/
https://www.amazon.co.uk/Sound-Effects-Vol-Nature-Animals/dp/B000M4RCXC/
https://www.amazon.co.uk/Sound-Effects-Vol-People-Sounds/dp/B000M4RCXM
https://www.amazon.co.uk/Sound-Effects-Vol/dp/B000M4RCXW/

Most sound effects are not game-ready and need to be mastered with software such as Audacity.