A MOA scope?
No.
But I don't know what you mean by MOA scope though???
You can't use anything to figure target size if target size & distance are unknown.
Best you can do is use your brain to figure what you think the target size should be.
And the range should be.
Or use an electronic range finder to find the exact range.
Then use your brain to figure out how big you think the target should be at that range.
The only problem is, in hunting, there are 100 pound deer, and 300 pound deer.
Or in war, 5' 3" humans, or 6'11" humans.
No scope or range finder can tell you the size of an unknown size target at an unknown range though.
Military snipers would use known sizes of vehicles, wheels, weapons, prior engagements in the same place, etc, with Mil Dot scopes to get pretty darn close though.
rc