Я думаю, что ты знаешь каждого здесь.

In a sentence like this, does the same logic for counting numbers apply, i.e. if it’s just 2-4 people you use “каждого” but past that you would need to use “каждых”? Or does it not work this way?

Hi! This sentence in Russian is correct for any number of people more than one. “Я думаю, что ты знаешь каждых здесь” is never correct .