I have only found one way to have a character that is 1.80 meters in Blender be 1.80 meters in Unreal with the entire skeleton hierarchy showcasing a scale of `1.0`. And that's by working in Blender with a "Unit Scale" at `0.01`.

```python
bpy.data.scenes["Scene"].unit_settings.scale_length = 0.01
```

If you are starting from a scene that's already been built at `1.0`, you can simply change the value to `0.01`, then scale your armature to `100` and use **Object > Apply > Scale** while the entire hierarchy is selected. This will "bake" the `100` scale into all the objects resetting the actual scale to `1.0`.

Export your FBXs with "Apply Unit" checked and "Scale" at `1.0`. Save an export. When importing in Unreal leave the default "Import Uniform Scale" to `1.0`. Below my current export script in Python for static and skeletal meshes.

```python
bpy.ops.export_scene.fbx(
    apply_unit_scale=True,
    bake_anim=False,
    filepath=r"C:\Your\File\Name.fbx",
    global_scale=1.0,
    mesh_smooth_type="FACE",
    object_types={"MESH", "ARMATURE"},
    use_selection=True,
)
```

There is a setting called "Apply Scalings" on export that I have not explored and that might provide an alternate way, but nothing is less sure.