While not exactly what you're requesting, immediately upon extracting the method, you can use
Alt/Opt+Enter > Add ApexDoc comment to generate an ApexDoc comment for the extracted method that takes into account its parameters and return type, e.g.:
which generates:
If you'd like to see something like
Generate ApexDoc comment as an option in the
Extract Method dialog, please log an enhancement request in the
public issue tracker which will ensure that it is more concretely on the list of candidates.
Regards,
Scott Wells