You can use 4k texture maps for a few different trees. Unless you’re going for a very high resolution look on your game 4k is more than enough for a few different models. You have to remember that even now, the most high end games out there don’t use 4k maps unless you custom build this stuff to look super realistic. Typically I use 2k maps in Unity. It’s really just personal preference but I rarely use 4k maps unless I’m going to combine a lot of textures together.
