Thanos used it to sense who was the real Strange in the battle of Titan.

There’s a deleted scene (from Infinity War), that shows Thanos using the Soul Stone to separate some of the Guardians’ souls from their bodies. This being a deleted scene does mean, however, that it is questionable on whether it is an actual capability. Just figured I’d mention it here anyway for interest, being as that’s one of the very few things we have on the stone’s power.

The Soul Stone may have been used to sort of erase the souls of the snap victims, which would mean they either went to the Soulworld or not. Even if that's not true, there is an answer ^^ 2 messages above me, that the Soul Stone was used to detect the real Strange. Which means the stone has been used on screen.

@Mvrr Endgame confirmed the Snapped victims didn’t go to the Soulworld, because Peter said everything went black, then he woke up.

Pay attention to the colors used every time Thanos activates the Stones during the fight on Titan.

It takes the Soul’s from anyone’s bodies which is why it’s called the Soul Stone

I kinds figuredit could be used to resurrect people but not people who died for it (gamora or black widow)

Which is still Dumb btw as that's not how the Soul Stone works in the Comic lol,