It’s fair to say that someone can have the power to influence, develop and enable without being officially recognised as the leader of a group of people. In many contexts, it is possible (necessary even) to exert influence even when not in a position of authority. This might happen in a meeting with a higher level of management, in a project situation, and in many other contexts.
French and Raven wrote extensively on the subject of leadership and power in the 1950s and 60s, and their ‘five powers’ thinking remains influential and insightful. In their model, one of the five powers is ‘referent’ power, which is the power to influence by role-modelling, or being seen as admirable and worthy of respect. Individuals who possess this power have the ability to be influential and attract followers, regardless of their actual level of authority.
In fact, some of the most influential leaders do not have the classic extrovert personality type. For example, Mahatma Gandhi and Mother Teresa did not command and control, but provided inspiring examples to their followers. This created a commitment that was stronger than the compliance generated through reward and punishment.