I don't think you'll get a standard answer for your question. My personal opinion is that a leadership style cannot be changed.
You probably already know that there are 3 main leadership styles:
- The Autocratic
- The Democratic
- The "Delegator"
Can you see the autocratic suddenly becoming democratic? Do you think it's possible for someone who's used to give orders and directions (without asking for opinion) to become someone who asks for everyone's opinion before taking a decision?
As you can see from the above, the leadership type is closely associated to the personality of the person, and the personality of the person cannot change once he's above his teen years, it is only shaped and never changed.