You can just choose between 2 sound formats mp3 and Ogg and Ogg is the winner here because it got a bit rate that can vary compared to mp3s constant one (pretty much wasting precious size!)
Also, try to keep everything as high quality as possible i would recommend just a slight compression because it the difference will be unnoticeable but chances are that the size will be much smaller.
Sounds are very underrated and many think that it isnt important to have high quality audio in your game but that’s just wrong.