Can a leader also be a follower?

Yes. A leader for some can be a follower for others. A leader can have a group of followers who admire him/her and are influenced by him/her but that leader can also admire and be influenced by another person. Being a leader doesn’t make a person immune to another person’s charisma and influence so a leader can be a follower as well. A good example is the hierarchy in organizations, there are plenty of leaders that are also followers and even the owner of the company will have someone who they admire and are influenced by, making them act as their follower even if in the company itself they are at the top. Even the biggest and most charismatic leaders in the world have someone that can influence them as a leader.