This is a paid asset, but now you can download Big Oak Free.
Detail this asset from Unity Store: Original Link
Big Oak v1.2
Big Oaks for HDRP, Universal, Built-in…
This pack includes:
● 4 big oak models with LOD’s (4 for each pipeline);
● Contains HDRP demoscene as it shows in video and screenshots: oaks, grass, terrain, light setup etc.;
● Contains Oak prefabs for Universal pipepline (ready to use prefabs only);
● Contains Oak prefabs for Built-in pipepline (ready to use prefabs only);
● Wind simulation for leaves and grass included (hdrp only);
● Simple park constructor;
● Oak leaves textures – 4K;
● Oak bark textures – 2K.
● oaks triangles:
– oak 1: lod0 32875 tris – lod1 14852 tris – lod2 6163 tris – lod3 537 tris;
– oak 2: lod0 18680 tris – lod1 6420 tris – lod2 421 tris;
– oak 3: lod0 18424 tris – lod1 4102 tris – lod2 565 tris;
– oak 4: lod0 23882 tris – lod1 8430 tris – lod2 649 tris.
● Contains HDRP demoscene as it shows in video and screenshots: oaks, grass, terrain, light setup etc.;
● Contains Oak prefabs for Universal pipepline (ready to use prefabs only);
● Contains Oak prefabs for Built-in pipepline (ready to use prefabs only).