I have looked at every total war series and there are oversized trees and stone why do them do it that is looks silly
Why it have bothered me sins the total war series began?
Almost all strategy games witha top-down view oversize stuff (not only trees, also units). Size perception is relative, and while from a first person view an elephant, a tree or a troll migth look huge, when you watch from above, the size difference is not that obvious.
Also, in TW you actually do a lot of fighting inside forests, if trees were real size, units and fights in general would probably be too hard to see and control, since when you zoomed in the view would be way too cluttered. The other option would be to highlight the units in bright colors, but that would probably result in an even more immersion-breaking system.
That's the system used in the Wargame series, which uses real scale enviroments. You decide which one you like better:
If anything the environment in total war is undersized. Real battles depending on the time period could stretch for miles. The whole reason napoleon could smash through enemy center lines and why you will horribly fail in total war is because the front line was a couple miles long, and by the time reinforcements got to the center the battle was over. In total war one army can easily stretch from 'wall' to 'wall'. I think since empire the maximum map size has only been 2x2 km.
Give a man a fish you feed him for a day, teach a man to fish you feed him for a lifetime.