Anytree is a Blender add-on from Bad Normals that grows a 3D tree from an approximate shape. You can model a form or draw it with curves, and the tool builds the tree from there. A set of parameters controls the shape and appearance, so you can steer the result toward the asset you have in mind.
Leaves and twigs are added with a toggle, drawing from a library of over 40 modelled by hand from real tree species. Each tree can receive correct UVs at the click of a button, and bark materials are included to texture it. The mesh uses optimized, controllable quad topology, and the tree mesh and leaves stay separate so they can be rigged or simulated.
The included add-on handles appending, duplicating and retargeting through simple controls, and a tutorial covers every aspect of the tool. The extension is published under an MIT license, and the developer states that updates are free going forward.