Hi Rodrigo.

You cannot do this in the Sheet metal environment because the material is being deformed. Sheet metal allows for Bends, which it calculates using a K-Factor, your Dome is not going to flatten, as the material is being distorted on 2 planes.

You could use the Unwrap command in Inventor (2020 version onwards), to flatten the dome once you have created the geometry.

https://clintbrown.co.uk/2019/03/27/inventor-2020-new-unwrap-command/