Can you briefly explain what the definition is of a 'property' and why 'existing' doesn't fit in it? The way I use the word property I don't see how it wouldn't apply to 'existing' or any other adjective for that matter
There are also relational properties, like being ten meters away from the Eiffel tower.
Some would call existence a second order property.
The Stanford encyclopedia of philosophy gives s good overview of the issues around existence. https://plato.stanford.edu/entries/existence/