Yes, Galaxy AI live call translator and interpreter can work offline, without internet connection, but only if you have a language packs downloaded to your phone.
The installation of Galaxy AI doesn't include the downloading of available language packs.
You have to download language packs that you need in:
Settings > Advanced features > Advanced intelligence > Interpreter > Language packs for translation
You can download all available Galaxy AI language packs for free. One language pack has around 500 MB.