Hi 3drenderings,
If I answered from memory (which I always avoid, if possible), I would say, use the Object Manager> Object> Project information.
Well, that works or not at all. At the moment, you have anything with instances, that can show up completely wrong, e.g., with Multi Instances. Some might argue about it, what counts, and what doesn’t.
Then there is the option to just select all objects and check the number in the first line of the Attribute Manager. It might show you 10000+.
Which means the default setting in the Preferences is set to 10000.
Main Menu> Edit> Preferences> Interface> Attribute Manager Selection Limit [10..100000].
As you can see with the numbers, the max is 100K here.
In the Object Manager, you can list the kind of things that are in the objects manager, it shows the exact number of existing objects (v. Instances). Object Manager: Most top/right icons, the second from the right.
So, the main question is, what is the need for it, what scene set up do you have?
Cheers