I heard dark energy is the intrinsic property of space and it cannot be particle because particle's density dilute when volume increase, I do not know how nothingness can have property and Einstein came up with a cosmological constant to fix his static universe model therefore mathematically he proved that space by itself can expand. Imagine a universe where empty space is devoided of energy and matter, can it expand?
The universe can expand without matter or radiation, but it cannot expand without energy. You can have “dark energy” without either matter or radiation.
In fact, right now dark energy is driving the accelerating expansion of our unverse, and the matter and radiation in it are playing a diminishing role. In the current standard cosmologcal model, the effect of matter and radiation will become negligible and the dark energy will cause exponential expansion.
You should not think of spacetime as nothingness. It has nontrivial geometric structure and the metric field that determines its geometry can carry energy, momentum, and angular momentum from place to place just like the electromagnetic field does.