There's any way to make .wav smaller?

[versed ridge]

.Wav files are lossless, meaning uncompressed. Technically, you can decrease their bit- or samplerate, but going lower than 16bit or 44.1KHz won't sound great.

Assuming you're asking in order to make music files smaller, you might want to go with OPUS encoding.
Check out the 1.6 mod report for more info: https://reforger.armaplatform.com/news/modding-update-november-4-2025

Note: There currently is a known bug where the .wav file actually doesn't get deleted when building the Addon. It should get fixed in the future.