There are some Open Theists who claim God is omniscient in the sense that God knows all possible future possibilities. This claim is not that God knows every single choice any free creature can currently make, but that God knows every free creature that could ever exist and all possible choices they can ever make. No matter what events happen throughout all of history into the future, God, before He created the world, knew those events as one such possibility out of many.
So when people say “God knows all possible outcomes” a Christian needs to stop and wonder “do you have any evidence for that or are you just making up what you want God to be like.” Does God want to know “all possible futures”? Is that something that even matters to God? Does the Bible talk like that about God? Or are we adopting pagan notions of perfection?
God does not talk in the Bible of “knowing all possible futures”.
A telling incident is when God asked the angels for suggestions. If God knew all possible futures, then surely God would not need to put on a farcical brainstorming session. The angel whose plan is adopted could have just been told by God to go do that activity. But the Bible depicts God as receiving suggestions and deciding between them:
1Ki 22:20 And the LORD said, Who shall persuade Ahab, that he may go up and fall at Ramothgilead? And one said on this manner, and another said on that manner.
1Ki 22:21 And there came forth a spirit, and stood before the LORD, and said, I will persuade him.
1Ki 22:22 And the LORD said unto him, Wherewith? And he said, I will go forth, and I will be a lying spirit in the mouth of all his prophets. And he said, Thou shalt persuade him, and prevail also: go forth, and do so.
The Bible is not overly concerned with God’s knowledge. God does not pride Himself in knowledge. God does not try to claim all knowledge. God does not even seem to believe that knowledge, for knowledge’s sake, is worth knowing. The pagan obsession with knowledge is just not present in the pages of the Bible.