The Kingdom of God is one of those misunderstood ideas as it is conflated with the Kingdom of Heaven, that they are the same thing, but Jesus uses them is a specific way which are different from each other.
The Kingdom of God is the spiritual reality of all those who have, or will exercise faith in the Lord Jesus Christ.. It is not a physical entity, it cannot be touched. It is spiritual reality.
Luke 17:21 Now when the Pharisees asked Jesus at what time the kingdom of God would begin, so He answered them, “You won't see the kingdom of God; nor will anyone be able to say, ‘See here!’ or ‘See there!’ Because the kingdom of God is within you.”
Matt 6:33 But you make it your first priority to seek out the kingdom of God and His righteousness, then all the things that you worry about, will be provided for you.
Matt 12:28 But if I am casting out demonic spirits by the Spirit of God, assuredly the kingdom of God has come near to you.