Refer to product images to know more about the average polycount in each plant specie.

This package was mainly made to be used in HDRP, there is a way to convert the assets to URP but it is important to know that the assets will not react to the translucency effect the same way and the thickness map will be missed in the Universal Render Pipeline. In the case of built-in render pipeline, it is not possible to use the shaders, you must replace them to render the vegetation correctly. You can find a quick solution in the unity assets store with tools like The Vegetation Engine.