maxtree offers free high poly trees as a free sample from every collection, you need to create an account to download these models which are available for both personal and commercial projects.
Maxtree - 3D Plant Models | CG Assets
Midge "Mantissa" Sinnaeve | Free CG Resources
Free 3d models - Trees - Viz-People
https://cgtricks.com/amp/download-free-forest-pack-3d-models-alter49/
