What God knows He means is true. How we interpret depends on how well the Holy Spirit has given us understanding.
It does say He made the universe and all in it, in six days. But it does not literally say how long those days were. If we claim how long they were, we are interpreting.
And I note how the creation was done before the fall of Adam and Eve, before sin entered the world. And our Apostle Paul says the creation was subjected to vanity, but later this whole creation will be changed into "the glorious liberty of the children of God." I offer this, based on Romans 8:20-21.
Possibly, I get through this scripture, the creation before the fall was not in a corruptible state. So, what could happen during twenty-four hours, then, could have been very different than after the fall of Adam and Eve.
We are the ones who can take a long time to do things. But God, being light, might be able to do things even faster than the speed of physical light. Twenty-four hours, then, for Him, could have been taking His time.