- do you English-speaking guys talk like this in real life or is it rather some kind of a formal way of expressing oneself?


"I demand that she be acquitted." Yep. That's how that would be expressed in this instance. Not that you couldn't express it differently. For example, "She better be acquitted or you're gonna eat my knuckle sandwich!"

I wouldn't expect to hear, "I demand she is acquitted!" Or "I demand she will be acquitted!" Or "I demand that she is acquitted!" Those would sound wrong, if not downright ungrammatical.