It's an infinite tree, you can make it any size you want.

The top and the first slice must be at the same scale

Each slice must be 20% larger than the previous one.
Ex : slice 1 : 100%, slice 2 : 120%, slice 3 : 144% (+20% of 120), etc

For the trunk, it must be enlarged to the same scale as the last slice

Doesn't Matter

No

0.2mm

10%

may need support for large expansions