Enoch and Elijah are in heaven. God took them into heaven before they died.
Heaven is not in space, so they’re not floating around in space. I’m not sure about the language of a different dimension either, but heaven is a place where Christians who die go to be with God and be in peace, awaiting the Last Day.
The chariot and horses were not ordinary, but “chariots of fire and horses of fire” and a “whirlwind”, which indicates something divine and supernatural. And it’s not random or fantastical. The reason God made this extraordinary sign was to grant Elisha’s request for a spiritual inheritance.
God is almighty, so He has the power to do anything. So when asking “How can God do this?” — the answer will always be the same: It’s possible because God is almighty. It’s much more profitable to ask “Why did God do this?” Then we can learn of God’s great love, mercy, and grace.
In the case of Enoch and Elijah, we can see God’s grace in redeeming them and the promise of life in Him; a new life without sin, death, pain, devil, and hell. As our Lord told the thief on the cross: “Today you will be with Me in paradise”. This is a promise to all of us who die believe in Jesus.